The document discusses how the curvature of compressor blades in a gas turbine system can contribute to loss of performance. Three blade sets with different curvatures (20°, 35°, 50°) were tested in a wind tunnel. The results showed that blades with higher curvature had higher points of flow separation and vortex height on the trailing edge, indicating poorer performance. Greater blade curvature leads to a higher possibility of issues like flow separation, turbulence, reduced pressure rise, and compressor stalling, all of which reduce the efficiency and power of the gas turbine system.
Iaetsd study and experimental analysis of linear and non linear behaviour ofIaetsd Iaetsd
The document describes an experimental study on the linear and non-linear behavior of pipe bends with ovality. Various pipe bend schedules including SCH 40 long radius, SCH 40 short radius, and SCH 80 short radius bends were tested under in-plane and out-of-plane bending moments both with and without internal pressure. Displacement and percentage change in ovality were measured in the intrados, crown, and extrados regions. The displacement in the intrados and extrados increased linearly with load. Allowable limit loads and ovality are suggested to avoid pipe rejection due to insufficient wall thickness. Mathematical and software results were compared to experimental results to optimize output.
Effect of punch profile radius and localised compressioniaemedu
This document discusses springback in V-bending of high strength steel sheets. It presents results from an experimental investigation and finite element analysis simulation of the effects of punch profile radius and localized compression on springback. The experimental results showed that increasing punch radius or decreasing sheet thickness increases springback, while applying localized compressive stress through bottoming the punch can compensate for springback. The finite element analysis validated the experimental findings. The document provides background on springback in bending, methods to compensate for it, and details of the materials testing and modeling approach used in the study.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Contact Pressure Validation of Steam Turbine Casing for Static Loading ConditionIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Studies on factors influencing the behavior of bolted flanged jointseSAT Journals
Abstract This article aims to study the parameters influencing the overall behavior of bolted flanged joints. Three dimensional finite ele-ment analysis has been extensively used to study the performance of bolted joints for eccentric tensile loading. Pretension in the bolt is modeled using ANSYS pretension element (PRETS179) which can be used on solid or line element types. Surface-to-surface contact elements are used to account for the contact pressure at various flange interfaces. The parameters considered for the study are bolt load, contact pressure between flanges and washers, flange opening and strains in the bolt. The effect of prel-oad on various parameters is studied. This paper illustrates the behavior of bolted flanged joints in entirety and brings out the effect of prying action on the bolted flanged joint. Index Terms— Bolt Load , Bolted joint, Contact Elements, Contact Pressure, External load, Pretension, Strains
IRJET- Comparision between Experimental and Analytical Investigation of Cold ...IRJET Journal
This document compares the experimental and analytical investigation of the structural behavior of cold formed steel angle sections under tension loading. 108 specimens of different cold formed steel angle sections with varying thicknesses were tested experimentally. The ultimate loads from the experiments were then compared to the predicted loads from several international design codes - Australian/New Zealand standard AS/NZS 4600-2005, American Iron and Steel Institute AISI Manual from 2001, and British Standard BS 5950-1998 Part 5. In general, the codes provided conservative predictions of the ultimate loads compared to the experimental values. Tables 1 and 2 show examples of the comparison between experimental and predicted ultimate loads for various angle section specimens.
This document discusses various modes of gear failure including abrasive wear, corrosive wear, pitting, and scoring. It provides details on the causes and remedies for each type of failure. The key points covered include:
- Mild and severe abrasive wear based on abrasive particle size and concentration. Remedies include oil filters and increasing surface hardness.
- Corrosive wear caused by lubricant chemistry or additives. Remedies include enclosure, additive selection, and oil changes.
- Initial and progressive pitting defined and causes explained as exceeding surface fatigue strength. Remedies include precision machining and load/stress reduction.
- Initial, moderate, and destructive scoring defined based on lubrication
1) The document reviews factors that influence the shear strength of reinforced concrete deep beams, including compressive strength of concrete, percentage of tension reinforcement, vertical and horizontal web reinforcement, aggregate interlock, shear span-to-depth ratio, loading distribution, side cover, and beam depth.
2) It finds that compressive strength of concrete, tension reinforcement percentage, and web reinforcement all increase shear strength, while shear strength decreases as shear span-to-depth ratio increases.
3) The distribution and amount of vertical and horizontal web reinforcement also affects shear strength, but closely spaced stirrups do not necessarily enhance capacity or performance.
Iaetsd study and experimental analysis of linear and non linear behaviour ofIaetsd Iaetsd
The document describes an experimental study on the linear and non-linear behavior of pipe bends with ovality. Various pipe bend schedules including SCH 40 long radius, SCH 40 short radius, and SCH 80 short radius bends were tested under in-plane and out-of-plane bending moments both with and without internal pressure. Displacement and percentage change in ovality were measured in the intrados, crown, and extrados regions. The displacement in the intrados and extrados increased linearly with load. Allowable limit loads and ovality are suggested to avoid pipe rejection due to insufficient wall thickness. Mathematical and software results were compared to experimental results to optimize output.
Effect of punch profile radius and localised compressioniaemedu
This document discusses springback in V-bending of high strength steel sheets. It presents results from an experimental investigation and finite element analysis simulation of the effects of punch profile radius and localized compression on springback. The experimental results showed that increasing punch radius or decreasing sheet thickness increases springback, while applying localized compressive stress through bottoming the punch can compensate for springback. The finite element analysis validated the experimental findings. The document provides background on springback in bending, methods to compensate for it, and details of the materials testing and modeling approach used in the study.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Contact Pressure Validation of Steam Turbine Casing for Static Loading ConditionIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Studies on factors influencing the behavior of bolted flanged jointseSAT Journals
Abstract This article aims to study the parameters influencing the overall behavior of bolted flanged joints. Three dimensional finite ele-ment analysis has been extensively used to study the performance of bolted joints for eccentric tensile loading. Pretension in the bolt is modeled using ANSYS pretension element (PRETS179) which can be used on solid or line element types. Surface-to-surface contact elements are used to account for the contact pressure at various flange interfaces. The parameters considered for the study are bolt load, contact pressure between flanges and washers, flange opening and strains in the bolt. The effect of prel-oad on various parameters is studied. This paper illustrates the behavior of bolted flanged joints in entirety and brings out the effect of prying action on the bolted flanged joint. Index Terms— Bolt Load , Bolted joint, Contact Elements, Contact Pressure, External load, Pretension, Strains
IRJET- Comparision between Experimental and Analytical Investigation of Cold ...IRJET Journal
This document compares the experimental and analytical investigation of the structural behavior of cold formed steel angle sections under tension loading. 108 specimens of different cold formed steel angle sections with varying thicknesses were tested experimentally. The ultimate loads from the experiments were then compared to the predicted loads from several international design codes - Australian/New Zealand standard AS/NZS 4600-2005, American Iron and Steel Institute AISI Manual from 2001, and British Standard BS 5950-1998 Part 5. In general, the codes provided conservative predictions of the ultimate loads compared to the experimental values. Tables 1 and 2 show examples of the comparison between experimental and predicted ultimate loads for various angle section specimens.
This document discusses various modes of gear failure including abrasive wear, corrosive wear, pitting, and scoring. It provides details on the causes and remedies for each type of failure. The key points covered include:
- Mild and severe abrasive wear based on abrasive particle size and concentration. Remedies include oil filters and increasing surface hardness.
- Corrosive wear caused by lubricant chemistry or additives. Remedies include enclosure, additive selection, and oil changes.
- Initial and progressive pitting defined and causes explained as exceeding surface fatigue strength. Remedies include precision machining and load/stress reduction.
- Initial, moderate, and destructive scoring defined based on lubrication
1) The document reviews factors that influence the shear strength of reinforced concrete deep beams, including compressive strength of concrete, percentage of tension reinforcement, vertical and horizontal web reinforcement, aggregate interlock, shear span-to-depth ratio, loading distribution, side cover, and beam depth.
2) It finds that compressive strength of concrete, tension reinforcement percentage, and web reinforcement all increase shear strength, while shear strength decreases as shear span-to-depth ratio increases.
3) The distribution and amount of vertical and horizontal web reinforcement also affects shear strength, but closely spaced stirrups do not necessarily enhance capacity or performance.
Abstract:In a typical keyed shaft connection where shock or reversing loads are to be transmitted, the clearance between key and keyway required for fitting is a serious disadvantage. The impact loads, generate a continuous pounding between key and keyway. This pounding frequently leads to shaft failures. The present project work presents a Keyless coupling. The device provides an ultimate solution by incorporating all the advantages of interference fits, while eliminating mounting and removal problems. Analysis is carried using ANSYS. The obtained results are compared with standard values. The standard values are taken for RINGFEDER catalog. The keyless data is taken from RINGFEDER. Here it has made an attempt in analyzing keyless coupling. From the results it can be concluded that keyless coupling is most suitable.
Keywords:coefficient of thermal expansion, interference fit, virtual shrink, Contact surface, wedge principle.
This document provides an abstract for a master's thesis on numerical analysis of residual stress on plate girders. The abstract indicates that the thesis addresses the prediction of imperfections in plate girders using simulation tools and simplified engineering models. It evaluates the impact of these imperfections, with a special focus on the effect of residual welding stress. Different simplified stress distributions are compared to results from welding simulation to validate recommendations on implementing weld-induced imperfections.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the type of Reinforced Concrete (RC) beams with transverse web openings. Various design approaches and strengthening techniques are also presented.
Cost Optimization of a Tubular Steel Truss Using Limit State Method of DesignIJERA Editor
Limit state method helps to design structures based on both safety and serviceability. The structures are designed to withstand ultimate loads or the loads at which failure occurs unlike working stress method where only service loads are considered. This leads to enhanced safety. Also unlike the working stress method, the structures are economical. It is also better than ultimate load method as serviceability requirement is also taken care of by considering various safety factors for all the load types and structures do not undergo massive deflection and cracks. For tubular sections, higher strength to weight ratio could result in upto 30% savings in steel .Due to the high torsional rigidity and compressive strength, Tubular sections behave more efficiently than conventional steel section This study is regarding the economy, load carrying capacity of all structural members and their corresponding safety measures.
Paper " STRUT-AND-TIE MODEL AND 3-D NONLINEAR FINITE ELEMENT ANALYSIS FOR THE...Waleed E. El-Demerdash
This document discusses the use of strut-and-tie modeling and 3D nonlinear finite element analysis to predict the behavior of reinforced concrete shallow and deep beams with openings. It presents the development of strut-and-tie models based on experimental results for selected beams. Finite element analysis using ANSYS is also employed for selected beams to complement the strut-and-tie model results. A parametric study investigates factors affecting beam behavior. Comparisons are made between finite element results, strut-and-tie model results, and experimental data.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Comparative Study on Anchorage in Reinforced Concrete Using Codes of Practice...IJERA Editor
This paper (Part II) reports a comparative study for BS8110 and EC2 of practice and those expressions by Batayneh and Neilsen on tests from literature. These have been treated under straight bar anchorages with transverse pressure. The aim of this study is to evaluate the reliability of the existing equations for bond strength of straight bars by applying to the available tests in the literature .The most important parameters were examined in these tests are concrete strength, anchorage length, concrete covers, bar diameter and transverse pressure. 264 tests from the literature have been chosen, which are all for straight bars with transverse pressure. The specimens are pull-out specimens with small concrete covers, beams ends and slabs. For both comparative studies in Part I and Part II, the conclusions and recommendations are presented here together.
IRJET- Analysis of Steel Silos Subjected to Wind Load with Various Slendernes...IRJET Journal
This document analyzes the structural behavior of circular thin-walled steel silos subjected to wind load with various slenderness ratios. Three finite element models of steel silos were created in SAP2000 with different height-to-diameter ratios (slenderness ratios): slender (4.2), intermediate (2.46), and squat (1.6). The models were analyzed under empty and full conditions to determine shell stresses and deformations. Results showed that deformation was highest for the slender silo when empty, but hoop stresses were highest for the squat silo when full. The analysis provides useful information for designing steel silos to withstand wind loads.
EFFECT OF TEMPERATURE IN ANALYSIS OF CREEP IN AN ISOTROPIC UNIFORM COMPOSITE ...ijiert bestjournal
The following paper discusses the effect of tempera ture in analysis of creep in an isotropic uniform composite cylinder. The paper is a part of the series of papers published under the analysis of creep in an isotropic uniform composite cylinder.
Conventional Design Calculation &3D Modeling of Metal Forming Heavy duty Hydr...IJERA Editor
This document summarizes the design and 3D modeling of a heavy-duty hydraulic press with a 300-ton capacity. It first describes performing conventional design calculations to size the main structural components, including beams, hydraulic cylinder, end caps, and glands. Finite element analysis is then conducted on a 3D model of the press to optimize the design and validate the stress levels calculated through conventional methods. The summary concludes that the conventional calculations estimated a stress of 150 kg/cm2 in the cylinder mounting plate, and further finite element analysis will be used to optimize the design.
This document summarizes research on the crushing behavior of aluminum and steel tubes with a cutout. A numerical model was developed using LS-DYNA software to simulate the quasi-static and dynamic crushing of tubes. Experiments were also conducted to validate the numerical model. The effects of parameters like material properties, strain rate, cutout location, tube length and impact speed on energy absorption were evaluated. Empirical equations were developed to describe the mean and peak crushing forces based on the numerical and experimental results.
This document discusses short columns and long columns according to IS 456:2000. It defines the unsupported length and effective length of columns. The slenderness ratio is used to determine whether a column is short or long. Short columns have slenderness ratios less than 12 and fail by crushing, while long columns have at least one slenderness ratio greater than 12 and fail by buckling. Two examples are provided to illustrate how to calculate the slenderness ratios and classify columns as short or long based on the ratios.
This document summarizes a study on optimizing the design of an electrostatic precipitator cone structure through finite element analysis. Two models (A and B) with different stiffener arrangements were analyzed under various loads. Model B with vertical stiffeners had the lowest deformation of 36.781 mm compared to Model A's minimum of 88.114 mm, though it was heavier. Increasing the stiffener size from 150x75mm to 400x100mm decreased the deformation for both models while increasing the weight. The maximum deformation region was found to be at the center of the largest surface area. Model B was determined to be safer but more costly due to higher material needs.
Experimental Investigation of Lateral Pressure on Vertical Formwork Systems u...IJTET Journal
The modeling of pressure distribution of fresh concrete poured in vertical formwork are rather dynamic than complex. Many researchers had worked on the pressure distribution modeling of concrete and formulated empirical relationship factors like formwork height, rate of pour, consistency classes of concrete. However, in the current scenario, most of high rise construction uses self compacting concrete(SCC) which is a special concrete which utilizes not only mineral and chemical admixtures but also varied aggregate proportions and hence modeling pressure distribution of SCC over other concrete in vertical formwork systems is necessitated. This research seeks to bridge the gap between the theoretical formulation of pressure distribution with the actual modeled (scaled) vertical formwork systems. The pressure distribution of SCC in the laboratory will be determined using pressure sensors, modeled and analyzed.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This master's thesis investigates the behavior of polygonal semi-closed thin-walled cross-sections under pure compression loading using finite strip analysis in CUFSM. The study focuses on elastic buckling only. Custom scripts were created to run CUFSM analysis on hexagonal, nonagonal and dodecagonal profiles. The results show that distortional buckling governs at higher spring values over 100 kN, but local and global buckling dominate at lower spring values. The half-wavelength values indicate required bolt densities. Considering the predominance of distortional buckling suggests the profiles do not behave rigidly.
Design of short circular axially loaded columngecnads
This document discusses the design of a short circular column with helical reinforcement subjected to axial loading. It provides the governing equations from the Indian standard code IS 456:2000 for calculating the load capacity and design of helical ties. As an example, it then shows the step-by-step design of a 400mm diameter column with M25 concrete and Fe415 steel subjected to 1,500kN axial load. The design satisfies all code requirements for tie spacing, size, and volume.
Simulation of Secondary Flow in Lubrication Pipe with End Bends of an Aero En...IRJET Journal
1) The document simulates oil flow behavior in the pressure pipe line of an aero engine using computational fluid dynamics (CFD). It examines the flow characteristics at five sections between the inlet and outlet.
2) Secondary flow develops at the bended sections due to curvature effects. Dean vortices form and their locations are visualized. Velocity decreases around the inner curvature and increases around the outer curvature.
3) Pressure drops slightly from 5 bar at the inlet to 4.9 bar at the outlet due to the short pipe length. Higher pressure variations occur around the bends.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The Value of SCADA Infrastructure Virtualization on Wind FarmsUpWind Solutions
SCADA infrastructure virtualization helps owners reduce the number of servers technical staff need to support and helps to create internal company equipment life cycle plans. It provides the technical staff with a more efficient and cost effective way to manage their servers and to protect their critical infrastructure.
Abstract:In a typical keyed shaft connection where shock or reversing loads are to be transmitted, the clearance between key and keyway required for fitting is a serious disadvantage. The impact loads, generate a continuous pounding between key and keyway. This pounding frequently leads to shaft failures. The present project work presents a Keyless coupling. The device provides an ultimate solution by incorporating all the advantages of interference fits, while eliminating mounting and removal problems. Analysis is carried using ANSYS. The obtained results are compared with standard values. The standard values are taken for RINGFEDER catalog. The keyless data is taken from RINGFEDER. Here it has made an attempt in analyzing keyless coupling. From the results it can be concluded that keyless coupling is most suitable.
Keywords:coefficient of thermal expansion, interference fit, virtual shrink, Contact surface, wedge principle.
This document provides an abstract for a master's thesis on numerical analysis of residual stress on plate girders. The abstract indicates that the thesis addresses the prediction of imperfections in plate girders using simulation tools and simplified engineering models. It evaluates the impact of these imperfections, with a special focus on the effect of residual welding stress. Different simplified stress distributions are compared to results from welding simulation to validate recommendations on implementing weld-induced imperfections.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the type of Reinforced Concrete (RC) beams with transverse web openings. Various design approaches and strengthening techniques are also presented.
Cost Optimization of a Tubular Steel Truss Using Limit State Method of DesignIJERA Editor
Limit state method helps to design structures based on both safety and serviceability. The structures are designed to withstand ultimate loads or the loads at which failure occurs unlike working stress method where only service loads are considered. This leads to enhanced safety. Also unlike the working stress method, the structures are economical. It is also better than ultimate load method as serviceability requirement is also taken care of by considering various safety factors for all the load types and structures do not undergo massive deflection and cracks. For tubular sections, higher strength to weight ratio could result in upto 30% savings in steel .Due to the high torsional rigidity and compressive strength, Tubular sections behave more efficiently than conventional steel section This study is regarding the economy, load carrying capacity of all structural members and their corresponding safety measures.
Paper " STRUT-AND-TIE MODEL AND 3-D NONLINEAR FINITE ELEMENT ANALYSIS FOR THE...Waleed E. El-Demerdash
This document discusses the use of strut-and-tie modeling and 3D nonlinear finite element analysis to predict the behavior of reinforced concrete shallow and deep beams with openings. It presents the development of strut-and-tie models based on experimental results for selected beams. Finite element analysis using ANSYS is also employed for selected beams to complement the strut-and-tie model results. A parametric study investigates factors affecting beam behavior. Comparisons are made between finite element results, strut-and-tie model results, and experimental data.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Comparative Study on Anchorage in Reinforced Concrete Using Codes of Practice...IJERA Editor
This paper (Part II) reports a comparative study for BS8110 and EC2 of practice and those expressions by Batayneh and Neilsen on tests from literature. These have been treated under straight bar anchorages with transverse pressure. The aim of this study is to evaluate the reliability of the existing equations for bond strength of straight bars by applying to the available tests in the literature .The most important parameters were examined in these tests are concrete strength, anchorage length, concrete covers, bar diameter and transverse pressure. 264 tests from the literature have been chosen, which are all for straight bars with transverse pressure. The specimens are pull-out specimens with small concrete covers, beams ends and slabs. For both comparative studies in Part I and Part II, the conclusions and recommendations are presented here together.
IRJET- Analysis of Steel Silos Subjected to Wind Load with Various Slendernes...IRJET Journal
This document analyzes the structural behavior of circular thin-walled steel silos subjected to wind load with various slenderness ratios. Three finite element models of steel silos were created in SAP2000 with different height-to-diameter ratios (slenderness ratios): slender (4.2), intermediate (2.46), and squat (1.6). The models were analyzed under empty and full conditions to determine shell stresses and deformations. Results showed that deformation was highest for the slender silo when empty, but hoop stresses were highest for the squat silo when full. The analysis provides useful information for designing steel silos to withstand wind loads.
EFFECT OF TEMPERATURE IN ANALYSIS OF CREEP IN AN ISOTROPIC UNIFORM COMPOSITE ...ijiert bestjournal
The following paper discusses the effect of tempera ture in analysis of creep in an isotropic uniform composite cylinder. The paper is a part of the series of papers published under the analysis of creep in an isotropic uniform composite cylinder.
Conventional Design Calculation &3D Modeling of Metal Forming Heavy duty Hydr...IJERA Editor
This document summarizes the design and 3D modeling of a heavy-duty hydraulic press with a 300-ton capacity. It first describes performing conventional design calculations to size the main structural components, including beams, hydraulic cylinder, end caps, and glands. Finite element analysis is then conducted on a 3D model of the press to optimize the design and validate the stress levels calculated through conventional methods. The summary concludes that the conventional calculations estimated a stress of 150 kg/cm2 in the cylinder mounting plate, and further finite element analysis will be used to optimize the design.
This document summarizes research on the crushing behavior of aluminum and steel tubes with a cutout. A numerical model was developed using LS-DYNA software to simulate the quasi-static and dynamic crushing of tubes. Experiments were also conducted to validate the numerical model. The effects of parameters like material properties, strain rate, cutout location, tube length and impact speed on energy absorption were evaluated. Empirical equations were developed to describe the mean and peak crushing forces based on the numerical and experimental results.
This document discusses short columns and long columns according to IS 456:2000. It defines the unsupported length and effective length of columns. The slenderness ratio is used to determine whether a column is short or long. Short columns have slenderness ratios less than 12 and fail by crushing, while long columns have at least one slenderness ratio greater than 12 and fail by buckling. Two examples are provided to illustrate how to calculate the slenderness ratios and classify columns as short or long based on the ratios.
This document summarizes a study on optimizing the design of an electrostatic precipitator cone structure through finite element analysis. Two models (A and B) with different stiffener arrangements were analyzed under various loads. Model B with vertical stiffeners had the lowest deformation of 36.781 mm compared to Model A's minimum of 88.114 mm, though it was heavier. Increasing the stiffener size from 150x75mm to 400x100mm decreased the deformation for both models while increasing the weight. The maximum deformation region was found to be at the center of the largest surface area. Model B was determined to be safer but more costly due to higher material needs.
Experimental Investigation of Lateral Pressure on Vertical Formwork Systems u...IJTET Journal
The modeling of pressure distribution of fresh concrete poured in vertical formwork are rather dynamic than complex. Many researchers had worked on the pressure distribution modeling of concrete and formulated empirical relationship factors like formwork height, rate of pour, consistency classes of concrete. However, in the current scenario, most of high rise construction uses self compacting concrete(SCC) which is a special concrete which utilizes not only mineral and chemical admixtures but also varied aggregate proportions and hence modeling pressure distribution of SCC over other concrete in vertical formwork systems is necessitated. This research seeks to bridge the gap between the theoretical formulation of pressure distribution with the actual modeled (scaled) vertical formwork systems. The pressure distribution of SCC in the laboratory will be determined using pressure sensors, modeled and analyzed.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This master's thesis investigates the behavior of polygonal semi-closed thin-walled cross-sections under pure compression loading using finite strip analysis in CUFSM. The study focuses on elastic buckling only. Custom scripts were created to run CUFSM analysis on hexagonal, nonagonal and dodecagonal profiles. The results show that distortional buckling governs at higher spring values over 100 kN, but local and global buckling dominate at lower spring values. The half-wavelength values indicate required bolt densities. Considering the predominance of distortional buckling suggests the profiles do not behave rigidly.
Design of short circular axially loaded columngecnads
This document discusses the design of a short circular column with helical reinforcement subjected to axial loading. It provides the governing equations from the Indian standard code IS 456:2000 for calculating the load capacity and design of helical ties. As an example, it then shows the step-by-step design of a 400mm diameter column with M25 concrete and Fe415 steel subjected to 1,500kN axial load. The design satisfies all code requirements for tie spacing, size, and volume.
Simulation of Secondary Flow in Lubrication Pipe with End Bends of an Aero En...IRJET Journal
1) The document simulates oil flow behavior in the pressure pipe line of an aero engine using computational fluid dynamics (CFD). It examines the flow characteristics at five sections between the inlet and outlet.
2) Secondary flow develops at the bended sections due to curvature effects. Dean vortices form and their locations are visualized. Velocity decreases around the inner curvature and increases around the outer curvature.
3) Pressure drops slightly from 5 bar at the inlet to 4.9 bar at the outlet due to the short pipe length. Higher pressure variations occur around the bends.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The Value of SCADA Infrastructure Virtualization on Wind FarmsUpWind Solutions
SCADA infrastructure virtualization helps owners reduce the number of servers technical staff need to support and helps to create internal company equipment life cycle plans. It provides the technical staff with a more efficient and cost effective way to manage their servers and to protect their critical infrastructure.
Windpower Engineering Webinar - Vortex Generators on Wind TurbinesUpWind Solutions
This document discusses vortex generators (VGs) that can be installed on wind turbine blades to improve their aerodynamic performance and energy production. It describes Smart Blade GmbH and UpWind Solutions' process for developing, testing, installing and analyzing the impact of customized VG solutions. Their VG design, installation procedure and testing aims to maximize energy production through stall delay and lift enhancement while minimizing noise and structural loads on the turbine. Case studies show VGs can increase annual energy production by 2-3% providing a strong return on investment.
Wind energy is a promising energy source. Modern wind power industry officially started in 1979 in Denmark with a
turbine of few KW and its evaluation brought up to now, devices of which rated power is higher than 20 MW.
The size of wind turbine’s massively increased and their design achieved a common standard device: Horizontal axis,
Three blades, Upwind, Pitch controlled blades, Active yaw system.
Stan Rosinski, Electric Power Research Institute - Speaker at the marcus evans Wind Power Summit held in Dallas, TX February 25-26, 2013 delivered his presentation entitled Technology Needs for Advancing Wind Power Generation
Vortex lattice modelling of winglets on wind turbine bladesDickdick Maulana
The document describes research into modeling winglets on wind turbine blades using vortex lattice methods. The goal is to understand how winglets influence airflow and aerodynamic forces. A free wake vortex lattice code and design algorithm were developed for steady-state horizontal axis wind turbines. Two winglet designs are analyzed in detail.
MSc_Thesis_Wake_Dynamics_Study_of_an_H-type_Vertical_Axis_Wind_TurbineChenguang He
This thesis investigates the wake dynamics of an H-type vertical axis wind turbine using particle image velocimetry (PIV). Two-component PIV is used to study vorticity shedding and horizontal wake expansion at the turbine mid-span plane. Stereoscopic PIV is performed on 7 cross-stream vertical planes to analyze tip vortex dynamics and the evolution of 3D wake structures. The experimental results show asymmetrical vorticity decay in the horizontal plane, with faster decay on the leeward side. Tip vortices are stronger than shed vortices. Near the turbine axis, tip vortices move inboard behind the rotor before moving outboard towards the windward side further downstream. Vertical
This webinar discussed proactive methods to reduce damage from transient turbine loads. It began with introductions and an overview of transient torsional events and how they can damage turbines. Data was presented showing that a reverse torsional damper can reduce the worst loads from such events by 50-70%. An analysis was shared that valued the impact of these load reductions on turbine components and estimated over $15,000 in annual savings per turbine. The presentation concluded by encouraging attendees to review the failure modes and effects analysis and white paper and to contact the presenters to discuss implementing load reduction solutions for increased reliability and returns.
This document describes a bladeless wind turbine that generates electricity through vortex shedding. It works by using the natural vortex shedding effect that occurs when wind flows past a bluff body, causing alternating vortices on each side. The oscillating vortices are used to drive a magnetic coupling system connected to an alternator to generate electricity. Key advantages are that it has a smaller structure than conventional wind turbines and can generate power at a lower cost. However, efficiency is lower than traditional designs and control systems are needed to manage oscillations at high wind speeds. The bladeless design has applications for power generation in remote areas.
Design of Adjustable Blade Wind Turbine for Constant Generated PowerRajeev Kumar
Wind turbines use the kinetic energy of the wind for generating the electricity by using ac generators.
The produced energy mainly depends on the wind speed and the swept area of the turbine. As the wind speed increases accordingly the dimensions of the blades of wind turbine reduces. The blades are made auto adjustable with the help of stepper motor and control unit mounted on it.
The wind turbine blades power and efficiency has been measured at different tip-speed-ratios and a maximum efficiency of 30% at 1.27 N/m3 air density.
Present work gives an insight into the design aspects of a wind turbine, like turbine blade design, wind power and output power calculation. This paper presents an idea to maintain the generated power constant at variable wind speed by changing the blade dimensions
The document predicts that governments will face increasing pressure to reduce greenhouse gas emissions. It also predicts that technologies to produce wind power and store energy will continue improving, leading to world energy from renewable sources growing as a portion of total energy production. These trends are expected to help reduce energy-related carbon dioxide emissions over time.
The document discusses potential benefits of downwind force-aligned rotors for extreme-scale offshore wind turbines. It describes how load alignment through concepts like morphing blades and pre-aligned blade segments could help reduce structural loads and mass. Steady-state analysis shows morphing could allow major reductions in blade and tower mass. Pre-alignment offers load savings with less complexity than morphing. Aerodynamic shrouds around the tower also help reduce wake effects. More analysis is still needed to determine the feasibility and benefits of these force-aligned downwind concepts.
Sandia National Laboratories has been conducting research on 100-meter wind turbine blades since 2009 to reduce technology risk and identify challenges of scaling up blade size. Their research has included developing detailed reference designs of 100-meter blades, studying advanced materials like carbon fiber and core materials, and investigating the effects of blade geometry and slenderness. Their work has resulted in four designs - SNL100-00 through SNL100-03 - each incorporating design improvements. All reference models, reports, and other materials from the project are publicly available online to support continued research on large wind turbine blades.
This document describes Wetzel Engineering's development of a modular space frame design for wind turbine blades. Some key points:
- The design aims to reduce weight, costs, and improve quality/inspection over conventional designs through a modular structure of spars and ribs connected by adhesive bonds rather than an infused shell.
- Motivations include enabling larger 100m blades for 10MW turbines through elimination of heavy core materials and large molds.
- Modularization also allows easier transportation and installation of large blades.
- Cost modeling of an 83m 6MW blade showed the space frame design could reduce costs by up to 22.5% over conventional designs.
The document describes a multidisciplinary optimization framework for designing wind turbine blades. The framework simultaneously optimizes the outer blade geometry and internal structural design. It is used to design a 10 MW rotor constrained not to exceed loads and mass of a reference 10 MW turbine. The optimization variables include blade chord, twist, thickness, prebend, and structural properties. The constraints include limits on chord, mass, loads and material failure criteria. The framework couples aerodynamic, aeroelastic and structural solvers to evaluate objectives like annual energy production during the optimization process.
This study investigates unsteady aerodynamic effects for a vertical axial wind turbine through computational fluid dynamics simulations. A two-dimensional model of the turbine was created using a NACA0015 airfoil for the blades. Simulations were run at different tip speed ratios to analyze blade forces, torque, and dynamic stall. Results showed that maximum average torque occurred at a tip speed ratio of 1.3. Blade forces were highest when the rotor was at 50 degrees. Dynamic stall phenomena, such as vortex shedding and detachment, were observed and affected turbine performance.
The document summarizes an experimental and numerical study of the effect of sweep on the three-dimensional flow downstream of axial flow fans. Three low-pressure axial flow fans were studied, with radial, forward, and backward sweep. Hot-wire anemometry was used to measure the velocity components downstream, and computational fluid dynamics (CFD) simulations using Reynolds-averaged Navier-Stokes (RANS) were performed for comparison. The results show that forward sweep decreases the radial velocity component while backward sweep increases it. The sweep also significantly influences the turbulent kinetic energy downstream of the fan.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Effect of flow coefficient and loading coefficient on the radial inflow turbi...eSAT Journals
Abstract
Before attempting to the design of radial inflow turbine, some of the techniques used to describe and present the effect of coefficient
on geometry, need to be appreciated. The user of turbine will generally require parameters which readily describe the overall
dimension of the machine so that assessments and comparisons can be easily made. The designer requires parameters which will
enable him to select the correct machine and make valid comparisons between competing designs. This allows the designer to
compute more easily the dimension of the machine at different coefficient, to assess the performance of a range of geometrically
similar machines. A paper describes the basic design parameters and effect of coefficient on radial inflow turbine impeller geometry
for 25kW application.
Index Terms: radial turbine design, flow and loading coefficient
IRJET- Study of Jet Impingement Heat TransferIRJET Journal
This document reviews research on jet impingement heat transfer. It discusses the flow and heat transfer characteristics of single and multiple impinging jets. Key factors that influence heat transfer are jet Reynolds number, nozzle-to-plate spacing, jet pattern, and crossflow. The document summarizes various empirical correlations that have been developed to predict average heat transfer coefficients. It also reviews numerical studies on modeling heat transfer for multi-jet systems and discusses the effects of parameters like Reynolds number, nozzle spacing, crossflow, and jet interference.
Parametric study of_centrifugal_fan_performance_exVnTunNguyn13
This document describes a study of centrifugal fan performance through experiments and numerical simulation. An experimental setup was developed to test fan prototypes and measure flow rate and power consumption. A computational fluid dynamics (CFD) model was also developed and validated against experimental results. Parametric studies were conducted to quantify the effects of number of blades, outlet angle, and diameter ratio on fan performance metrics like power coefficient, flow coefficient, efficiency, and pressure coefficient. The results provide insight on how fan performance is affected by geometric parameters and operating conditions.
Numerical Investigation of Single Stage of an Axial Flow Compressor for Effec...IJERA Editor
In present work, a compressor configuration is taken from literature which will be studied for aspect ratio (ratio between length of blade to chord length) influence over performance. Performance in the sense is pressure ratio of compressor. The aspect ratio of the blade is an important parameter and has a strong influence on the performance of axial flow compressor. There are so many literatures available on influence of design parameters of axial flow compressor over its performance. Few literatures only are available for effects of aspect ratio of blade over performance of compressor. A study is proposed to be carried out to verify the effect of aspect ratio on the performance of single stage subsonic compressor through ANSYS-CFX software. The analysis will be carried out for the constant tip diameter of the compressor rotor blade having an aspect ratio 1, 2 and 3 and to obtain the pressure loss and flow parameters of the compressor stage. Further increase in aspect ratio will lead to structural problem of compressor. Therefore, there will be optimum aspect ratio between 2 and 3. Simulation will be conducted to aspect ratios of 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 and 2.9 to find optimum ratio using ANSYS-CFX commercial CFD software.
This document discusses aeroelastic analysis of a moving wind turbine blade using fluid-structure interaction (FSI) modeling. The analysis used ANSYS software to simulate the interaction between fluid flow and structural stresses on the blade. The results showed maximum tip deflection and stresses at the blade root. Accounting for FSI is important as fluid forces can significantly impact blade stresses and vibrations over time.
INVESTIGATION EFFECTS OF BACKWARD AND FORWARD BLADE SKEW MODES APPLIED TO AXI...IRJET Journal
This document summarizes a study that investigated the effects of backward and forward blade skew modes applied to axial flow turbo machinery using computational fluid dynamics (CFD) tools and analysis of experimental data from literature. Low-aspect-ratio rotors with forward and backward skew were modeled and their performance was compared to an unskewed datum rotor at various flow rates, spanwise positions, and efficiencies. The CFD results showed that at the design flow rate, forward skew reduced radially outward flow along the span, especially near the tip. It also provided greater efficiency up to 75% of the blade span compared to other rotors. Near the tip, forward skew increased inlet axial velocities and decreased them at smaller radii. Outlet axial
Numerical Investigation Of Compression Performance Of Different Blade Configu...IJERA Editor
This project work is to investigate the compression efficiency of different configuration of Turbo-Prop Co-Rotor Blade System of Subsonic Axial Flow Compressor. By this method the highly compressed air can be passed over the intake of the engine to the compressor with high mass flow rate in change of low velocity and high pressure ratio. The length of the small rotor is varied in terms of large rotor length by 25,50 & 75% . Each will have three space configuration in terms of diameter of rotor and in the percentage of 5,10,15%. A total of 12 configurations will be simulated to arrive optimum blade configuration. The blades are made in the shape of an airfoil like wing of an aircraft. The engine rotates the propeller blades, which produce lift. This lift is called thrust and moves the aircraft forward. Blades are usually made of high lift airfoil which allows more rotation to generate high pressure for engine. ANSYS- Fluent is commercial software which is robust for most of the fluid dynamic problems and it is used in this project work to evaluate the different configurations of co-rotor propeller system to arrive the best.
This project work is to investigate the compression efficiency of different configuration of Turbo-Prop Co-Rotor Blade System of Subsonic Axial Flow Compressor. By this method the highly compressed air can be passed over the intake of the engine to the compressor with high mass flow rate in change of low velocity and high pressure ratio. The length of the small rotor is varied in terms of large rotor length by 25,50 & 75% . Each will have three space configuration in terms of diameter of rotor and in the percentage of 5,10,15%. A total of 12 configurations will be simulated to arrive optimum blade configuration. The blades are made in the shape of an airfoil like wing of an aircraft. The engine rotates the propeller blades, which produce lift. This lift is called thrust and moves the aircraft forward. Blades are usually made of high lift airfoil which allows more rotation to generate high pressure for engine. ANSYS- Fluent is commercial software which is robust for most of the fluid dynamic problems and it is used in this project work to evaluate the different configurations of co-rotor propeller system to arrive the best.
Numerical Analysis of Lift & Drag Performance of NACA0012 Wind Turbine AerofoilIRJET Journal
This document discusses numerical analysis of lift and drag performance for a NACA0012 wind turbine airfoil. Two airfoil models were analyzed: one with a regular surface and another with circular dimples added to the upper surface. Computational fluid dynamics software was used to calculate the coefficient of lift and drag at various angles of attack. The results showed that adding dimples to the upper surface increased the lift to drag ratio compared to the regular airfoil surface, indicating improved aerodynamic performance from controlling flow separation with the dimples.
IRJET- Simulation and Experimental Analysis of Blower for Performance Improve...IRJET Journal
This document summarizes a study on using the Coanda effect to improve the performance of a blower. The Coanda effect is the tendency of a fluid jet to attach to a nearby surface. The researchers 3D modeled different surfaces in CATIA and simulated air flow over them in ANSYS Fluent to analyze the Coanda effect. They also conducted experiments with a blower passing air over physical surfaces. Both simulations and experiments showed that angling surfaces from 45 to 90 degrees and using cylindrical surfaces increased the pressure drop and airflow velocity near vent openings, improving the blower's outlet discharge. The results validate using the Coanda effect to enhance a blower's performance.
Review of a Shrouded Wind Turbine for Low Wind Speedsdbpublications
The use of renewable energy is promoted
worldwide to be less dependent on fossil fuels
andnuclear energy. Therefore research in the field
is driven to increase efficiency of renewable energy
systems. This study aimed to develop a wind
turbine for low wind speeds. The extent of power
increase, or augmentation, the factors influencing
shrouded wind turbine performance, the optimal
geometry and economical benefit remained
unanswered.
The most important matter at hand when dealing
with a shrouded wind turbine is to determine if the
overall diameter or the blade diameter of the
turbine should be the point of reference. As the
wind turbine is situated in a shroud that has a larger
diameter than the turbine blades, some researchers
believe that the overall diameter should be used to
calculate the efficiency Theory was revised to
determine the available energy in the shroud after
initial calculations showed that the power
coefficients should have been higher than the open
wind turbine with the same total diameter. A new
equation was derived to predict the available
energy in a shroud.
Design and Development of Transonic Axial Flow Compressor Rotor BladeIJERDJOURNAL
Abstract:- This paper is about a new computational fluid dynamics developed for the transonic flow in a compressor rotor. Due to 3-Dimensional blade modification the arrangements satisfying the required boundary condition. Engine compressor towards distorted inflow has to be taken in account which is already in the design phase. Flow separation over the blade surface reduction and elimination can improve better aerodynamic, performance, efficiency and stall margin. NASA transonic rotor tip critical in baseline blade rotor performance energizing the low momentum boundary layer, controlling the inception of stall. A Profile generator are attached on the inner casing of the rotor ahead to the loading edge of the rotor and it is influenced on the overall performance which has been studied.
CFD Analysis for Computing Drag force on Various types of blades for Vertical...IRJET Journal
This document discusses a computational fluid dynamics (CFD) analysis of drag forces on various blade profiles for vertical axis wind turbines (VAWTs). Three blade profiles were analyzed: a conventional airfoil blade (EPPLER863), the EPPLER863 profile with one-fourth of the trailing edge removed, and a Lenz2 type turbine blade profile. The CFD analysis found that the Lenz2 profile generated the maximum drag force of 11.21 Newtons and had the lowest drag coefficient of -7.5, indicating it is the most suitable option for VAWTs in urban areas with typical wind speeds of 6-10 m/s. Modifying the EPPLER863 profile was partially successful
IRJET- Effects of Dimples on Aerodynamic Performance of Horizontal Axis W...IRJET Journal
This document discusses research into the effects of adding dimples to the surfaces of horizontal axis wind turbine blades. It aims to investigate how dimples impact the aerodynamic performance of wind turbine blades. The researchers used computational fluid dynamics software to simulate flow over a baseline wind turbine blade design with and without various dimple configurations. The simulations found that blades with dimples experienced delayed flow separation, resulting in enhanced aerodynamic performance and increased power extraction compared to the baseline blade without dimples. Validation with experimental wind tunnel testing of a scaled down model supported the numerical results.
This document discusses various aerodynamic models used to predict the performance of straight-bladed vertical axis wind turbines (VAWTs). It first describes momentum models, including the rotor blade model and single streamtube model. The rotor blade model calculates forces on blade sections, while the streamtube model represents the turbine as an actuator disk. It then introduces the double-multiple streamtube model which divides the swept volume into streamtubes and calculates upstream and downstream induced velocities. The document also discusses experimental wind tunnel tests using laser Doppler velocimetry and pressure sensors on turbine blades to measure velocities and pressures and validate the momentum model calculations.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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Poor blade curvature a contributor in the loss of performance in the compressor unit of gas turbine systems
1. Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
Poor Blade Curvature - A Contributor in the Loss of Performance in
the Compressor Unit of Gas Turbine Systems
Chigbo A. Mgbemene
Department of Mechanical Engineering, University of Nigeria, Nsukka 410001
chigbo.mgbemene@gmail,com , +2348034263781
Abstract
The relationship between the curvatures of the blade and the loss of performance of the compressor unit of the gas
turbine system was studied. Three blade sets of three different blade curvatures 20o, 35o and 50o were fabricated for
this investigation. The blades were tested in a manually fabricated wooden wind tunnel and points of flow separation
and vortex height on the trailing edge of each blade set were recorded. The obtained results were then analyzed with
respect to the blade velocity distribution effects, compressibility effects and blade loading effects. The analysis
indicates that the larger the blade curvature the higher the possibility of poor performance of the system.
Keywords: blade curvature, flow separation, vortex height, velocity, blade loading, stagnation, pressure, suction
surface.
1. Introduction
The profile of the gas turbine blades, be it the compressor or turbine blades, has proven to be the most sensitive area
of study in the gas turbine plant. Highly expensive brainpower and a lot of man-hours are invested in order to find
the blade configurations which will be stable and efficient within specified working angles. Blades must be designed
to have correct aerodynamic shape and also be light, tough, and not prone to excessive noise and excessive
vibrations. Blades must also be designed to achieve substantial pressure differentials per stage. All these mentioned
have direct or indirect relationships to the profile of the blade.
In actual situation, the profile of the compressor and the turbine differ. Higher pressure differentials per stage are
achieved in the turbine unit than in the compressor hence fewer stages of turbines are required to drive the
compressor unit. The turbine blade profile exhibits deeper curvatures than that of the compressor. This is because the
air flow in the compressor is more sensitive to the curvature of the blade profile than it is in the turbine blade profile
and if deep curvatures are attempted, the ensuing effects are generally undesirable. Studies have shown that if such
curvature is attempted in the compressor blade profile, air flow will tend to separate from the blade surface leading to
turbulence, reduced pressure rise, stalling of the compressor with a concurrent loss of engine power and lowered
efficiency of the system [1], all which could be termed loss of performance. Theoretically, deeper curvatures should
give higher system performance but in the actual situation, loss of performance of the system occurs. For example,
stalling of the compressor airfoil blade (which is a loss of performance parameter) results when flow separation
occurs over a major portion of the airfoil’s suction surface. If the angle of attack of an airfoil is increased, the
stagnation point moves back along the pressure surface of the airfoil. The flow on the suction surface then must
accelerate sharply to round the nose of the airfoil. The minimum pressure becomes lower, and it moves forward on
the suction surface. A severe adverse pressure gradient appears following the point of minimum pressure; finally, it
causes the flow to separate completely from the suction surface inducing form drag and the airfoil stalls [2, 3]. A
detailed presentation of the review of the studies on stalling and surging of the compressor could be found in Ref.
[4].
There are other influences in the system which lead to the poor performance for example, according to Cardamone in
Ref. [5] the state of the boundary layer influences, in a major way, the loss development and this loss development
directly bears on poor performance of the system.
You and Moin in Ref. [6] presented that flow separation on an airfoil surface is related to the aerodynamic design of
the airfoil profile; and that the nature of flow separation on an airfoil is closely related to the performance of the
system. From the presentations of Refs. [5, 6] and Hulse et al [7] flow boundary layer separation is related to the
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airfoil profile and the performance of the system. Ref. [7] and Bertagnolio et al [8] were able to relate that the blade
type affects sound generation by the blade while showing that noise level is also a form of performance measure of
the system. They presented that the variations of the separation point along fixed blades, in turn, produce changes in
the form of their wake and contribute to the discrete-frequency interaction noise from the rotor.
Indeed, several studies have been carried out on the performance of the axial compressor blade but the studies have
concentrated more on the stalling and surging of the axial compressor. But again it has been stated that careful design
of compressor blading is necessary to prevent wasteful losses and minimize stalling [9].
To the perception of the author, the effect of the curvature, even to its possible contribution to the stalling and
surging of the compressor has not been shown in simple terms for easier understanding. This write-up therefore aims
at presenting the relationship between the curvatures of the blade and the loss of performance of the gas turbine
system. The effect of the curvature with respect to this loss of system performance was surmised in this paper from
the testing of blades with different curvatures. This was done by investigating the relationship between curvatures of
the blade with respect to the point of flow separation and vortex height on the trailing edge and subsequently relating
them to the velocity distribution effects and blade loading effects due to compressibility effects on the axial type
system. This study was carried out by fabrication of model blade cascades at three different blade angles of 20o, 35o
and 50o. Each cascade was tested and the results obtained were analyzed. The paper is meant to give the reader a
basic idea of the effects of blade curvature in the loss of performance of the gas turbine system.
2. Experimental Approach
2.1 Evaluation of the blade profile
According to Cohen [10] two major requirements of a blade row, whether rotor and stator, are to turn the air through
the required angle (β1 – β2) in case of the rotor and (α2 – α3) in the case of the stator; and secondly, carry out
diffusing process with optimum efficiency i.e. with minimum loss of stagnation pressure. Consequently, the angle at
which the air flows across the blades is critical to the performance of the compressor [11]. One fact remains that air
will not leave a blade precisely in the direction indicated by the blade outlet angle, factors like velocity of the air and
pressure ratio will affect the exit point. For this reason, to obtain a good performance over a range of operating
conditions, it is wise not to make the blade angle equal to the design value of the relative air angle.
According to Cohen [10] the design of blades is much of an art. The design of the blade starts with the sketch of the
base profile like as in Fig. 1, from which the blade shape is obtained. The base profile can be constructed or can be
determined from the Joukowski transformation of a given circle. It can be defined as the basic shape of an airfoil
with a straight camber line (where the camber length equals the chord) as shown in Fig. 2(a) [10].
For subsonic flows, it is necessary to use airfoil section blading to obtain a high efficiency but for increased Mach
number flows, blade sections based on parabolas are more effective [10]. For this work, the experiment was carried
out in subsonic flow therefore; the base profile with the airfoil shape was used for the blade design. The rotor and
stator blades have the same profile and camber arc but are arranged as shown in Fig. 2(b). The base profile generally
used for gas turbine blade shape design is the NACA 4-digit series [12]. Details about the design of blades abound in
literatures such as in Refs. [10, 12, 13, and 14] but that is not the point of this paper; therefore, this will not be fully
discussed.
2.2 The blade design
The ordinates of the base profile t1 and t2 are given at definite positions along the camber-line as shown in Fig. 2(a).
With the ordinates known the value of the YU and YL are computed as
tn × l
YU , YL = (1)
100
where tn = already specified ordinates in Fig. 2(a) as t1 and t2
n = 1 and 2 for upper and lower sections of the profile respectively
l = camber length (chord).
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According to Perkins and Hage [12], in the design of the blade, the centre of the leading edge radius is usually
obtained by drawing a line through the end of the chord with slope equal to slope of camber line at 0.5 percent of
chord and laying off the leading edge radius along this line. The position of maximum thickness is always 30 percent
of the chord [10, 15]. The ratio of maximum thickness and chord (t/c) for blade shapes is generally 10 percent [16].
Following this, the Y values (YU and YL) were computed and laid off at calculated points on the X axis.
A chord length of 70mm and a blade height of 100mm were chosen for the sake of handling and the size of the wind
tunnel that will be used for the testing. A suitable pitch/chord ratio (s/c) of 0.57 (to achieve a high air deflection) [10]
and a stagger angle of 34o were chosen. The choices were made based on the actual data from blade samples
obtained from gas turbine blades of Afam Power Station Port Harcourt Nigeria which were Asea Brown Boveri gas
turbines whose deflection curves agreed with the typical design deflection curve presented in Ref. [10]. Since the
blades were to be curved, a circular arc camber line was assumed and the blades were constructed for θ = 20o, 35o
and 50o. The blades operate in cascades with notation as shown in Fig. 3. Figure 4 shows the constructed blades
(three sets) which were used for the subsequent tests.
2.3 The low speed wind tunnel (smoke tunnel)
The experiment warranted setting up a special test rig to test the designed blades. A special wind tunnel - an open
circuit (or Eiffel) type tunnel was constructed. Because of the size and nature of the experiment, a smoke tunnel was
found suitable for the tests [17]. Smoke was introduced ahead of the model being tested. Very low flow speeds were
employed for the test to produce a laminar flow into the test section and to avoid the diffusion of the smoke. The
wind tunnel was made of wood. It consisted of a smoke pot, a circular duct, rectangular plenum, a rectangular duct
with adjustable section (inflow duct), transparent Perspex top, an exit duct, a rectangular chimney and a suction fan.
Except the suction fan, every other equipment was locally fabricated with either wood or paper. The arrangement of
the wind tunnel is as shown in Fig. 5.
Figure 6 shows front and plan view of the constructed smoke tunnel with a set of blades being tested. The smoke was
generated by burning spent engine oil (SAE 40) on embers in a smoke pot and was channeled into the inflow duct
through a circular duct. The size of the inflow duct of the tunnel was adjusted such that air (smoke) entered each set
of blades at its designed β1 angle. The air (smoke) was drawn in through suction by the fan placed at the end of the
chimney. The fan speeds were measured with a Kestrel 3000 digital meter capable of measuring air velocity,
temperature, and humidity. Provision was not made for the variation of the spacing between the blades. The
observation of the behaviour of air through the blades was visual hence the use of smoke as the fluid medium.
3. Methodology
The tests were carried out with the smoke moving at subsonic speed. Different low speeds were used according to
the fan suction speed settings. The speeds were:
(i) N. speed (NS) – 3.3m/s
(ii) Speed 1 (S1) – 5.2m/s
(iii) Speed 2 (S2) – 10.0m/s
Each blade set was placed between the adjustable duct and the exit chimney. The fan (at a given speed) sucked the
smoke through the set of blades. The behaviour of the smoke through the set of blades was observed through the
Perspex cover. The points of separation from the leading edge of the blade were recorded as well as the height of the
vortex formed on the suction surface at the trailing edge. These were done for the three different fan speeds at three
different incidence angles (denoted as in Fig 7) and the results recorded. The average values of each set were
obtained and were used in the subsequent plot. Although four different sets of plot namely:
(i) Vortex vs separation graph
(ii) Variation of angle vs average separation graph
(iii) Speed vs average separation graph
(iv) Average vortex vs speed graph (for the 20o @ (-10o) result only)
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could be used to describe the results of the experiment, just one set vortex vs separation graph (Fig. 8) is enough for
explanations, therefore only that was shown in this paper.
4. Results and Discussions
Separation of flow occurs when the boundary layer has traveled far enough against an adverse pressure gradient such
that its energy level drops to a level that the boundary layer speed relative to the object falls almost to zero, the flow
then detaches from the object and leaves in form of vortices and eddies. From this study, the point of this separation
was found to be affected by, amongst other parameters, the velocity of the flow.
The values of the distance of the points of separation from the leading edge of the blade and the heights of the vortex
formed on the suction surface at the trailing edge were recorded and plotted as shown in the Figs. 8 - 10.
Comparing the graphs in sets for the specified angles of 20o, 35o and 50o @ (i = 0o); then 20o, 35o and 50o @ (i =
+10o) and 20o, 35o and 50o @ (i = -10o); for the vortex height vs separation point graph (Fig. 8), it could be seen that
as the camber angle was decreased or increased, the point at which separation started on the blade decreased or
increased respectively. The vortex height also increased or decreased along with the camber angle’s increment or
decrement respectively. For each angle series for example, 50o @ (i = 0o, +10o and -10o), it could be observed that a
variation in the angle of attack of the air on the blade (Fig.9) affected the behaviour of the air in the blade set. A
general trend was observed that as the angle of attack varied from 0o, the point of separation got closer to the leading
edge (Fig.10). It was also observed that the negative series (-10o) gave lower separation points but also gave the
lowest vortex heights (Figs. 8 and 9), but for the 20o @ (-10o) the air separated on hitting the leading edge of the
blade resulting in higher vortex than would be expected given the foregoing trend.
A study of the effect of air speed variations with respect to each blade showed that the lower the speed, the higher the
separation point or higher the speed, the lower the point of separation.
In the 50o @ (-10o), a reversal of trend was noticed; instead of separation point decreasing with increasing speed, it
rather increased with increasing speed (Fig. 9a). The separation point despite this reversal was still lower than that of
the specified angle 50o @ (0o). This may have arisen due to the air hitting the blade at an angle such that the laminar
boundary layer separated. According to Cardamone [5] and Anderson et al [18] in the presence of adverse pressure
gradients, if the laminar boundary layer separates, transition may take place in a shear layer over the separation
bubble. Since a turbulent shear layer has much higher diffusion capability than a laminar one, the flow reattaches
usually shortly after transition. This may have been the reason for the trend in the 50o @ (-10o).
It was also observed that for any given speed the flow stayed longer on the blade suction surface before separation on
the shallower curved blades (Figs. 9 and 10). Vortex heights increased as the speeds were increased leading to
turbulent wakes.
Apart from the abnormal behaviour of the air in the 50o @ (-10o) blade position, it was observed that generally as the
speed was increased the air gradually lost its ability to negotiate curves and then separated from the blade. The
degree of separation and formation of vortex depended on the degree of curvature of the blade and also the angle of
attack. This effect could be explained by the work of Perkins and Hage in Ref. [12]. They presented that the degree
of separation on an aerodynamic body is largely dependent on the magnitude of the unfavourable pressure gradient to
the rear of the point of minimum pressure or maximum surface velocity. Therefore, if the pressure gradient, dp/dx,
along the surface from this point is equal to or less than zero, then no separation exists. But when the pressure
gradient is gradual, the separation occurs so near the rear of the body such that only a very small turbulent wake is
produced and the boundary layer is extremely thin everywhere. The drag created by such a body is small and arises
mostly from skin friction. If the pressure gradient is high, separation occurs well forward of the rear stagnation point
and a turbulent wake exists which alters the potential-flow picture and pressure distribution.
4.1 The consequences of the curvatures
The consequences of a large blade curvature could be seen when the stagnation pressure ratio in a blade row given as
Eq. (2) [1] is looked at.
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γ (γ −1)
(γ − 1)M 0 2 ω
[(rv )2 − (rv )1 ]
ps 2
= 1 + (2)
1 + γ − 1 M 0 2 w0
2
p s1
2
where ps1 and ps2 are the stagnation pressures at stations 1 (ahead) and 2 (aft) of the cascade.
From the equation, it could be seen that achieving a large stagnation pressure in the cascade can only be done by
having a large curvature but it introduces two deleterious effects – velocity distribution and blade loading effects. A
large stagnation pressure will also introduce a large adverse static pressure gradient which leads to boundary layer
separation on the blade.
4.1.1 The velocity distribution effect due to the blade curvature
Since the air passing over an airfoil will accelerate to a higher velocity on the convex surface and in a stationary row,
this will give rise to a drop in static pressure. This convex surface is termed the suction side of the blade. The
concave side will experience a deceleration of the flow and a rise in static pressure hence it is termed the pressure
side (Fig 7). Given similar conditions, the velocity distribution through the passage between the pressure side and the
suction side will be as presented in Refs. [10, 19] as shown in Fig.11. The maximum velocity on the suction surface
will occur at around 10 – 15 percent of the chord from the leading edge after which it falls steadily until the outlet
velocity is reached. It was found that relatively thick surface boundary layers resulting in high losses occur in regions
where rapid changes of velocity occur, i.e. in regions of high velocity gradient. From Fig. 7, this would most likely
occur on the suction surface of the blade. Then increasing the convex nature of the suction surface would increase
the velocity gradient further leading to a serious loss due to friction and breakdown of flow with its attendant drop in
stagnation pressure.
4.1.2 Blade loading effects
A large blade curvature will lead to a high blade aerodynamic loading and low values of minimum static pressure on
the blade suction side [1] and compressibility effects affect the blade loading in that they change the pressure
distributions along the blade so that the blade loadings may become excessive. This pressure distribution is related to
the permissible deflection in the blade. For a given peripheral speed, the pressure rise obtained in a stage is a
function of a coefficient of deflection τ, which for a particular degree of reaction depends on the permissible
deflection ∆β of the flow in the cascades [20]. This was shown by Carter [21] and Zweifel [22].
Let us consider the study done by Carter based on observations of an N.G.T.E.[23] profile test data as shown in
Fig.12, measured in a 5 in – low speed cascade tunnel of NACA for subsonic flow; here θ = ∆β = 18.6o, the static
pressures p on the profile was obtained by means of the pressure coefficients cp. The values of cp at stations (1) and
(2) are given as:
p s1 − p 1 (3)
cp 1 =
(ρ / 2 )V1 2
ps2 − p2 (4)
cp 2 =
(ρ / 2 )V2 2
where ps1 and ps2 are the total stagnation pressures ahead and aft of the cascade velocities V1 and V2 respectively. For
an incompressible flow with friction, it is possible to express the frictional losses by the drop of the absolute
stagnation pressures at the stations ahead (1) and aft (2) of the cascade. This reduction in absolute stagnation pressure
is identical with that of the relative total pressure pSR, since the stream surfaces are coaxial cylinders. The loss
through a cascade has also been related to the ideal velocity head which could be produced by a frictionless process
between the stagnation pressure ps1 and the static pressure p2. However, if the velocity diagram Fig.13 [24] is to
represent the actual velocities that occur for a process with friction, then the pressure coefficient cp will be given as
p SR1 − p SR 2 p S1 − p S 2
cp (ξ ) = = (5)
(ρ / 2)V2 2
(ρ / 2)V2 2
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Neglecting geopotential energy differences, the difference in relative pressures can be given as
p SR1 − p SR 2 = p1 − p 2 + (ρ / 2) V1 − V2( 2 2
) (6)
Combining Eqs. (5) and (6) we have
( 2 2
)
p 2 − p1 = (ρ / 2) V1 − V2 − ξ (ρ / 2)V2
2
(7)
The normal force F on the blade can then be represented as
Cos 2 β ∞ Sinβ ∞
F = sρV∞ ∆Vu − ξs (ρ / 2 )V ∞ (8)
2
Cos 2 β 2
Neglecting the second term we have that
F ≈ sρV∞ ∆Vu (9)
Introducing the solidity σ = blade chord/blade spacing
σ = (c / s ) , (10)
and if we express the normal force in terms of the lift coefficient CL which is dimensionless, then
F . (11)
CL =
(ρ / 2)V∞ 2 c
Combining Eqs. (9) and (11) then
2∆Vu (12)
CL =
σV∞
From Fig.13 CL can then be expressed as
2
CL = [tan β1 − tan β 2 ]cos β 2 (13)
σ
From Eq. (13) the link between the permissible deflection and the pressure distribution could be deduced via the lift
coefficient. It could also be deduced that the force on the blade depends on the pressure gradient on the suction side
of the blade which in turn is affected by the degree of fluid deflection. Therefore, increasing the blade curvature ends
up increasing the blade loading.
5. Conclusions
The relationship between the curvatures of the blade and the loss of performance of the gas turbine system has been
studied. The discussions have shown that as the curvature was increased from 20o to 50o, the points of separations
receded and vortex heights increased and consequently, the detrimental factors that lead to stall and surge in the
system were accentuated. Blade aerodynamic loading and the velocity gradient increased with increasing curvature
leading to a serious loss due to friction and breakdown of flow with its attendant drop in stagnation pressure.
Following these, it can then be concluded that large blade curvature in compressors lead to early flow separations
with its adverse effects in the whole compressor system. Therefore, designing blades with large curvatures will lead
to loss of performance in the compressor system.
Acknowledgements
The author would like to thank Prof. H. I. Hart of Rivers State University of Technology Port Harcourt and the
management of Afam Power Station, Port Harcourt Nigeria for their support towards this project.
References
[1] Oates, G. C., 1988, Aerothermodynamics of Gas Turbine and Rocket Propulsion (Revised and Enlarged),
AIAA Educational Series, American Institute of Aeronautics and Astronautics, Inc., Washington D.C.
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ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
[2] Kay, J. M. and Nedderman, R. M., 1974, An Introduction to Fluid Mechanics and Heat Transfer, 3rd Ed.,
Cambridge University Press, Cambridge, UK.
[3] Fox, R. W. and McDonald, A. T., 1978, Introduction to Fluid Mechanics, 2nd Ed., John Wiley and Sons, New
York.
[4] Mgbemene, C. A., 2002, “The Effect of Blade Curvature in the Failure of Gas Turbine Blades,” M.Eng. Thesis,
University of Nigeria, Nsukka, Enugu State.
[5] Cardamone, P., 2006, “Aerodynamic Optimization of Highly Loaded Turbine Cascade Blades for Heavy Duty
Gas Turbine Applications,” Ph.D Thesis, Universität der Bundeswehr München, Germany.
[6] You, D. and Moin, P., 2006, “Large-Eddy Simulation of Flow Separation over an Airfoil with Synthetic Jet
Control,” Center for Turbulence Research Annual Research Briefs, pp 337 – 346,
http://ctr.stanford.edu/ResBriefs06/26_You1.pdf, accessed 16 Jan. 2012.
[7] Hulse, B. T., Lange, J. B., Bateman, D. A. and Change, S.C., 1966, “Some Effects of Blade Characteristics
on Compressor Noise Level,” FA65WA-1263, Federal Aviation Administration, Washington, D.C.
[8] Bertagnolio, F., Madsen, H. A. and Bak, C., 2010, “Trailing edge noise model validation and application to
airfoil optimization,” Journal of Solar Energy Engineering, 132, pp 031010-1 - 031010-9.
[9] Bhushan, N., 2008, “Flow through Centrifugal & Axial Flow Compressors,” http://www.leb.eei.uni-
erlangen.de/winterakademie/2008/report/content/course01/pdf/0112.pdf, accessed 23 Feb. 2012.
[10] Cohen, H., Rogers, G. F. C. and Saravanamuttoo, H. I. H., 1988, Gas Turbine Theory, 3rd Ed., Longman
Scientific and Technical, Harlow Essex, UK, Chap. 4.
[11] Anonymous, 2012, “Fundamentals of Gas Turbine Engines,” http://www.cast-
safety.org/pdf/3_engine_fundamentals.pdf, accessed 16 Jan. 2012
[12] Perkins, C. D. and Hage, R. E., 1958, Airplane Performance Stability and Control, John Wiley & Sons, Inc.,
New York, Chap. 2.
[13] Dixon, S. L., 1998, Fluid Mechanics and Thermodynamics of Turbomachinery, 4th Ed., Butterworth-
Heinemann, Boston, MA.
[14] Horlock, J. H., 1958, Axial Flow Compressors, Butterworths Scientific Publications, London.
[15] Carter, A. D. S., Turner, R. C., Sparkes, D. W. and Burrows, R. A., 1960, “The Design and Testing of an
Axial-Flow Compressor having Different Blade Profiles in Each Stage,” Reports and Memoranda, Ministry of
Aviation, Aeronautical Research Council, London, A.R.C. Technical Report No. 3183.
[16] Boyce, Meherwan P., 2002, Gas Turbine Engineering Handbook, 2nd Ed., Gulf Professional Publishing,
Boston, Chap. 7
[17] Pope, A. and Harper, J. J., 1966, Low Speed Wind Tunnel Testing, John Wiley and Sons Inc., New York.
[18] Anderson, D. A., Tannehill, J. C. and Pletcher, R. H., 1984, Computational Fluid Mechanics and Heat
Transfer, Hemisphere Publishing Corporation, New York, NY, pp 374 - 375.
[19] Elmstrom, M.E., 2004, “Numerical Prediction of the Impact of Non-Uniform Leading Edge Coatings on the
Aerodynamic Performance of Compressor Airfoils,” Master’s Thesis, Naval Postgraduate School, Monterey,
CA.
[20] Sinette, J. T. Jr., Schey, O. W. and King, J. A., 1943, “Performance of NACA Eight Stage Axial Flow
Compressor Designed on the Basis of Airfoil Theory,” NACA Report 758, Washington D.C.
[21] Carter, A. D. S., 1955, “The Axial Compressor,” Gas Turbine Principles and Practice, Sir H. R. Cox (Ed.),
G. Newnes Ltd, London, Section 5.
[22] Zweifel, O., 1945, “Optimum Blade Pitch for Turbo-Machines with Special Reference to Blades of Great
Curvature,” Brown Boveri Review, 32.
[23] Felix, A. R. and Emery, J. C., 1957, “A Comparison of Typical National Gas Turbine Establishment and
NACA Axial Flow Compressor Blade Sections in Cascade at Low Speed,” NACA Technical Note 3937,
Washington D.C.
[24] Vavra, M. H., 1962, Aero-Thermodynamics and Flow in Turbomachines, John Wiley & Sons, Inc., New
York, NY.
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The Figures
Y
YU
X
l=c
Fig. 1: An aerofoil blade profile.
t1 t2
L.E. O
0 0 β1′
2.08 2.63
3.00 3.12
3.58 3.66 A
4.01 4.06
4.55 4.88 D
4.90
Camber line Chord
4.89
C Rotor
Camber-line length l
4.98 5.02
ζ
YU YL
4.76 4.79
B
β2′
4.30 4.31 Centre of
camber
3.70 3.72
arc
2.91 3.00
2.02 2.15
Stator
1.05 1.20
0.60 0.68
0 0
O
Upper T.E. Lower
L.E. = Leading edge
Surface Surface
(a) T.E. = Trailing edge (b)
YU (%l) YL (%l)
Fig. 2: (a) The blade base profile. (b) The rotor and stator layout in blade design.
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Front of Air flow
Position of compressor direction
maximum β1′ = blade inlet angle
thickness β1 β2′ = blade outlet angle
β1 ′ V1 θ = blade camber angle
o o
θ = 20 , 35 and 50 o = β1′- β2′
ζ = setting or stagger angle
i s = pitch
a ε = air deflection = β1 - β2
ζ
β1 = air inlet angle
Rotor β2 = air outlet angle
c V1 = air inlet velocity
Point of
maximum camber V2 = air outlet velocity
i = incidence angle = β1 - β1′
β2′ s
δ = deviation angle = β2 - β2′
δ c = chord
Radius of t = maximum thickness
Direction of drum rotation β2 camber arc a = distance of maximum
V2 camber from L.E.
Fig. 3: Compressor cascade and blade notation.
(a) (b) (c)
Fig. 4: The fabricated blade samples (a) θ = 20 (b) θ = 35 and (c) θ = 50o.
o o
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Inflow duct Blade set under
test
Air (smoke)
inlet
Suction fan
Wind tunnel
(fixed section) Inflow duct
adjuster
Fig. 5: A schematic diagram of the wind tunnel with a blade set in place.
Suction
fan
Exit
chimney
Smoke pot
(a) (b)
Flow control section Blades under test
Fig. 6: (a) Front view and (b) Plan view of the wind tunnel.
35
11. Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
Suction surface y
β1 θ = 20o, 35o and 50o
-10o
Air (smoke) out
0o +10o
Air x Pressure surface
(smoke) Incidence angle
in
Fig. 7: The blade test nomenclature.
15
N ( 50 o @ 0 o )
S
S ( 50 o @ 0 o )
1
V rte h ig t [m ]
m
S ( 50 o @ 0 o )
2
10
N ( 35 o @ 0 o )
S
S ( 35 o @ 0 o )
1
o x e h
S ( 35 o @ 0 o )
2
N ( 20 o @ 0 o )
S
5
S ( 20 o @ 0 o )
1
S ( 20 o @ 0 o )
2
0
0 10 20 30 40 50 60 70
Po t o Sep ratio
in f a n [m ]
m
Fig. 8: A plot of Point of Separation against Vortex Height for the (a) θ = 20o,
(b) θ = 35o and (c) θ = 50o blade sets at i = 0o.
36
12. Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
20 15
50o Blad Set
e NS @ 0o 35o Blad Set
e
N @ 0o
S
o o
S1 @ 0 S @0
1
Vortex Height [mm]
Vortex height [mm]
15 S2 @ 0o S @ 0o
2
10
N @ +10o
S NS @ +10o
S @ +10o
1 S @ +10o
1
10 (b)
(a) S @ +10o
2 S @ +10o
2
5 N @ -10o
S
N @ -10o
S
5
S @ -10o
1 S @ -10o
1
S @ -10o
2 S @ -10o
2
0 0
0 5 10 15 20 25 30 35 40 45 50 25 30 35 40 45 50
Po t o Sep
in f aratio [m ]
n m Po o Sep
int f aration [m ]
m
10
NS @ 0o 20o Blade Set
S1 @ 0o
Vortex Height [mm]
S2 @ 0o
N @ +10o
S
S @ +10o
1
5
(c) S @ +10o
2
0
10 15 20 25 30 35 40 45 50 55 60 65 70 75
Po t o Sep
in f aratio [m ]
n m
Fig. 9: A plot of Vortex Height vs. Point of Separation.
37
13. Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
PS2
PS1 y (mm)
PNS
15
S2 S1
Air NS 0
o
in i=0 x
(mm
0 20 40 60 70
48.5
(a) 55.2 65.2
PS1
PS2 PNS
y (mm)
S2 S1 15
NS
Air 0
in i = 0o x
(mm)
0 20 40 60 70
39.3 46.0
(b) 44.5
PS1
PS2 PNS
y (mm)
S2 S1 15
NS
Air 0
in i = 0o x
(mm)
0 20 50 70
30.0 42.2
(c) 38.7
Fig. 10: Points of separation PNS, S1, S2 (x axis) and vortex heights (y axis) for the (a) θ = 20o,
(b) θ = 35o and (c) θ = 50o blade sets.
Vmax
Suction surface
V1
Mean velocity in
V2
Pressure
0 Chord percent 100
Fig. 11: Typical velocity distribution through the passage of a cascade set [10, 19].
38
14. Journal of Energy Technologies and Policy www.iiste.org
ISSN 2224-3232 (Paper) ISSN 2225-0573 (Online)
Vol.2, No.4, 2012
Suction side
1 ∆β = 18.6o pu
β1 = 60o 2
V2
o
15.6 pl Pressure side
44.4o β2 = 41.4o
V1
x
c
+1
C
pl − p2 0 A
cp l =
(ρ / 2)V2 2
Pressure side cpl
-1
pu − p2 2⅓ K = 3.1
cp u =
(ρ / 2)V2 2 3
-2
Suction side cpu
-3
B
-4
0 0.6 0.2 0.8 1.0
0.4
x/c
Fig. 12: Measured pressure distribution on profile NGTE 10C4/30C50 in cascade [23].
F
D o
90
ε
Fa 90o
β∞ Fe
β∞
Fu
β1 Va
Axial
β∞
direction
β2
V1 V∞ V2
ΔV Vu2
V u1 + V u 2
2
Vu1
½ΔVu ½ΔVu
Fig. 13: Velocity diagram of axial flow compressor cascade [24].
39
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