This document discusses a study that uses computational fluid dynamics (CFD) software to analyze flow characteristics in a centrifugal pump. Specifically:
1. CFD software called CFX is used to simulate fluid flow through a 3D model of a centrifugal pump with defined boundary conditions.
2. The software helps optimize the pump design in an iterative manner based on results like pressure and velocity plots.
3. A key issue analyzed is cavitation, where vapor bubbles form and collapse in the pump due to low pressure. The document examines factors that cause cavitation and its negative effects.
Pressure distribution around a circular cylinder bodies | Fluid Laboratory Saif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
A cylinder in a closed circuit wind tunnel will be experimented upon
to gather the pressure distribution acting on it
Laminar flow is defined when a fluid flows in parallel layers, with no
disruption between the layers. In comparison to this Turbulent flow
has a much more disorganized pattern, it is characterized by
mixing of the fluid by eddies of varying size within the flow.
The Reynolds number (Re), gives the measure for laminar and
turbulent flows. Laminar flow takes place when Reynolds number
is lower than 104, and for Turbulent flow the Re must be greater
than 3Ã-105.
The pressure is measured using the manometer, and then
therefore the pressure at the tapping must be the same as the
pressure head.
The cylinder being experimented on is placed in the wind tunnel.
The pressure upstream of the cylinder is sensed by a taping on the
tunnel wall and is connected to one of the tubes.
Performance, Optimization and CFD Analysis of Submersible Pump Impellerijsrd.com
To improve the efficiency of submersible flow pump, Computational Fluid Dynamics (CFD) analysis is one of the advanced tools used in the pump industry. A detailed CFD analysis was done to predict the flow pattern inside the impeller which is an active pump component. From the results of CFD analysis, the velocity and pressure in the outlet of the impeller is predicted. CFD analyses are done using ANSYS CFX software. In this research paper we will modified the impeller design by choosing some parameter.
This paper deals with the numerical analysis of 3d model which has inlet port diameter 46mm,valve diameter 43mm and the length and diameter of the cy linder is 562mm and 93.65mm respectively which is developed to study the effect of valve lif t on the flow of fluid inside the cylinder. For different valve lifts velocity will change inside t he cylinder. Results of CFD simulation indicated th at valve lift affects velocity flow field inside the c ylinder. It also proved that CFD is a convenient to ol for designing and optimizing the flow field in the engine.
Pressure distribution along convergent- divergent NozzleSaif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
This aim of this practical was to investigate compressible flow in a
convergent-divergent nozzle. Different flow patterns that influence
the results of the investigation are also explored. The different
pressure distributions that occur at varying lengths in the nozzle
were also recorded and analyzed
Pressure distribution around a circular cylinder bodies | Fluid Laboratory Saif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
A cylinder in a closed circuit wind tunnel will be experimented upon
to gather the pressure distribution acting on it
Laminar flow is defined when a fluid flows in parallel layers, with no
disruption between the layers. In comparison to this Turbulent flow
has a much more disorganized pattern, it is characterized by
mixing of the fluid by eddies of varying size within the flow.
The Reynolds number (Re), gives the measure for laminar and
turbulent flows. Laminar flow takes place when Reynolds number
is lower than 104, and for Turbulent flow the Re must be greater
than 3Ã-105.
The pressure is measured using the manometer, and then
therefore the pressure at the tapping must be the same as the
pressure head.
The cylinder being experimented on is placed in the wind tunnel.
The pressure upstream of the cylinder is sensed by a taping on the
tunnel wall and is connected to one of the tubes.
Performance, Optimization and CFD Analysis of Submersible Pump Impellerijsrd.com
To improve the efficiency of submersible flow pump, Computational Fluid Dynamics (CFD) analysis is one of the advanced tools used in the pump industry. A detailed CFD analysis was done to predict the flow pattern inside the impeller which is an active pump component. From the results of CFD analysis, the velocity and pressure in the outlet of the impeller is predicted. CFD analyses are done using ANSYS CFX software. In this research paper we will modified the impeller design by choosing some parameter.
This paper deals with the numerical analysis of 3d model which has inlet port diameter 46mm,valve diameter 43mm and the length and diameter of the cy linder is 562mm and 93.65mm respectively which is developed to study the effect of valve lif t on the flow of fluid inside the cylinder. For different valve lifts velocity will change inside t he cylinder. Results of CFD simulation indicated th at valve lift affects velocity flow field inside the c ylinder. It also proved that CFD is a convenient to ol for designing and optimizing the flow field in the engine.
Pressure distribution along convergent- divergent NozzleSaif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
This aim of this practical was to investigate compressible flow in a
convergent-divergent nozzle. Different flow patterns that influence
the results of the investigation are also explored. The different
pressure distributions that occur at varying lengths in the nozzle
were also recorded and analyzed
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.
Pipe insulation efficiency study unit |HEAT TRANSFER LaboratorySaif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
1. Experiment Name: Pipe Insulation Efficiency Study Unit
2. Experiment Aim: The study unit for the assessment of thermal
insulation efficiency permits investigating the effect of thermal
insulation of steam pipes, the unit consist of a set of four pipes, three of
which are covered with insulating materials, placed vertically. Steam is
fed by means of an overhead manifold
3. Composition:
The lagging of piping unit includes:
1. - 3 test pipes covered with materials which thermal conductivity
coefficient is different.
2. One pipe without covering,
3. Manual control valve on steam inlet,
4. Bourdon pressure gauge on steam inlet
5. Thermometer in steam inlet
6. Condenser discharge system,
7. Graduated containers of glass to measure the condensate,
Pressure Distribution on an Airfoil
The team conducted the experiment to determine the effects of pressure distribution on lift and pitching moment and the behavior of stall for laminar and turbulent boundary layers in the USNA Closed-Circuit Wing Tunnel (CCWT) with an NACA 65-012 airfoil at a Reynolds number of 1,000,000. The airfoil was tested in a clean configuration at angles of attack of 0, 5, 8, 10, and 12 degrees. Tape added to the leading edge tripped the boundary layer, and pressure distributions were taken at 8, 10, and 12 degrees angle of attack. Experimental results showed a suction peak at less than 1% of chord, providing a beneficial test article for contrast between smooth and laminar boundary layer behavior at the stall condition. The maximum lift coefficient for the clean airfoil was 0.9 at 10 degrees angle of attack, and tripped airfoil reached a maximum lift coefficient of 1.03 at 12 degrees angle of attack, a 14% increase. These data were 10% lower than the empirical airfoil data found in Theory of Wing Sections from Abbott and von Doenhoff. Pitching moment coefficient about the quarter chord remained near zero below stall as expected for a symmetrical airfoil, but rapidly became negative after stall for experimental and empirical data. The airfoil exhibited a leading edge stall for both laminar and turbulent boundary layers.
Oil & Gas Pipelines are often subjected to an operation called ‘Pigging’ for maintenance purposes (For e.g., cleaning the pipeline of accumulated liquids or waxes). A pig is launched from a pig launcher that scrapes out the remnant contents of the pipeline into a vessel known as a ‘Slug catcher’. The term slug catcher is used since pigging operations produces a Slug flow regime characterized by the alternating columns of liquids & gases. Slug catcher’s are popularly of two types – Horizontal Vessel Type & Finger Type Slug catcher. However irrespective of the type used, the determination of the slug catcher volume becomes the primary step before choosing the slug catcher type.
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.
Modeling and Analysis of Wholesale Competitive Electricity Markets: A Case Fo...IJERA Editor
Electricity markets all over the world are moving towards greater reliance on competition and this has become a global trend as a method of best practice. However, before competition is introduced in electricity markets it is imperative to model and assess the behavior of the market. The assessment includes calculating the market performance indices to determine the levels of market power exploitation by the Generating Companies (GenCos) that will participate in the market. This paper presents a study on modeling and analysis of wholesale competitive electricity market for a developing country to help regulators assess and predict market behaviour. It involves modeling and simulation of the Zambian power system network in Agent-Based Modeling of Electricity Systems (AMES) using real system data to pick out critical information that enables us to assess the status of the market. The results indicate that market power exploitation is prevalent for the two largest GenCos assessed.
Single Mode Optical Fiber in Rof System Using DWDMIJERA Editor
Performance analysis was carried out to find the effect of crosstalk in a WDM system. Firstly, analysis of BER
was carried out without crosstalk. Then analysis of BER with crosstalk was done. Using equation for crosstalk,
number of channels was plotted using matlab. System parameters were optimized for a particular crosstalk.
Objective of the thesis work
Performance Analysis is carried out to find the effect of crosstalk due to optical cross connect in a DWDM
system considering a WDM based optical cross connect (OXC). An analysis is carried out to find the amount of
crosstalk due to OXC. The bit error rate performance degradation due to crosstalk is evaluated for OXC
parameter and number of wavelengths per fiber. The optimum parameters such as optimum number of channels
and hops are determined.
Numerical Study of Star Anchor Plate Embedded in Cohesive SoilIJERA Editor
Indonesia as an archipelago country has a very long coastline about 90.000 kms. Specifically for shore and offshore, there are many buildings utilizing structures including floating deck, mooring dolphin, offshore platforms etc. Those requires a solution to maintain the stability of the structures due to the vertical movement of tides and horizontal movement of currents, wind and waves. To maintain the stability due to buoyant force, structure of anchors are needed. Various types of the anchor have been widely used such as drag, helical, anchor plate circular shape and square. This study aims to do the development of new modifications of a plate anchor type star with 4 leaves with an area of a fixed and diameter equivalent different on any variations. Ultimate pullout capacity was obtained by using numerical geomechanics analysis within finite difference method. A perfectly plastic soil model was used with a tresca yield criterion. Results are presented including break-out factors based on various anchor shapes and embedment depth. Our findings are also compared with previous numerical and empirical solutions.
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.
Pipe insulation efficiency study unit |HEAT TRANSFER LaboratorySaif al-din ali
SAIF ALDIN ALI MADIN
سيف الدين علي ماضي
S96aif@gmail.com
1. Experiment Name: Pipe Insulation Efficiency Study Unit
2. Experiment Aim: The study unit for the assessment of thermal
insulation efficiency permits investigating the effect of thermal
insulation of steam pipes, the unit consist of a set of four pipes, three of
which are covered with insulating materials, placed vertically. Steam is
fed by means of an overhead manifold
3. Composition:
The lagging of piping unit includes:
1. - 3 test pipes covered with materials which thermal conductivity
coefficient is different.
2. One pipe without covering,
3. Manual control valve on steam inlet,
4. Bourdon pressure gauge on steam inlet
5. Thermometer in steam inlet
6. Condenser discharge system,
7. Graduated containers of glass to measure the condensate,
Pressure Distribution on an Airfoil
The team conducted the experiment to determine the effects of pressure distribution on lift and pitching moment and the behavior of stall for laminar and turbulent boundary layers in the USNA Closed-Circuit Wing Tunnel (CCWT) with an NACA 65-012 airfoil at a Reynolds number of 1,000,000. The airfoil was tested in a clean configuration at angles of attack of 0, 5, 8, 10, and 12 degrees. Tape added to the leading edge tripped the boundary layer, and pressure distributions were taken at 8, 10, and 12 degrees angle of attack. Experimental results showed a suction peak at less than 1% of chord, providing a beneficial test article for contrast between smooth and laminar boundary layer behavior at the stall condition. The maximum lift coefficient for the clean airfoil was 0.9 at 10 degrees angle of attack, and tripped airfoil reached a maximum lift coefficient of 1.03 at 12 degrees angle of attack, a 14% increase. These data were 10% lower than the empirical airfoil data found in Theory of Wing Sections from Abbott and von Doenhoff. Pitching moment coefficient about the quarter chord remained near zero below stall as expected for a symmetrical airfoil, but rapidly became negative after stall for experimental and empirical data. The airfoil exhibited a leading edge stall for both laminar and turbulent boundary layers.
Oil & Gas Pipelines are often subjected to an operation called ‘Pigging’ for maintenance purposes (For e.g., cleaning the pipeline of accumulated liquids or waxes). A pig is launched from a pig launcher that scrapes out the remnant contents of the pipeline into a vessel known as a ‘Slug catcher’. The term slug catcher is used since pigging operations produces a Slug flow regime characterized by the alternating columns of liquids & gases. Slug catcher’s are popularly of two types – Horizontal Vessel Type & Finger Type Slug catcher. However irrespective of the type used, the determination of the slug catcher volume becomes the primary step before choosing the slug catcher type.
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.
Modeling and Analysis of Wholesale Competitive Electricity Markets: A Case Fo...IJERA Editor
Electricity markets all over the world are moving towards greater reliance on competition and this has become a global trend as a method of best practice. However, before competition is introduced in electricity markets it is imperative to model and assess the behavior of the market. The assessment includes calculating the market performance indices to determine the levels of market power exploitation by the Generating Companies (GenCos) that will participate in the market. This paper presents a study on modeling and analysis of wholesale competitive electricity market for a developing country to help regulators assess and predict market behaviour. It involves modeling and simulation of the Zambian power system network in Agent-Based Modeling of Electricity Systems (AMES) using real system data to pick out critical information that enables us to assess the status of the market. The results indicate that market power exploitation is prevalent for the two largest GenCos assessed.
Single Mode Optical Fiber in Rof System Using DWDMIJERA Editor
Performance analysis was carried out to find the effect of crosstalk in a WDM system. Firstly, analysis of BER
was carried out without crosstalk. Then analysis of BER with crosstalk was done. Using equation for crosstalk,
number of channels was plotted using matlab. System parameters were optimized for a particular crosstalk.
Objective of the thesis work
Performance Analysis is carried out to find the effect of crosstalk due to optical cross connect in a DWDM
system considering a WDM based optical cross connect (OXC). An analysis is carried out to find the amount of
crosstalk due to OXC. The bit error rate performance degradation due to crosstalk is evaluated for OXC
parameter and number of wavelengths per fiber. The optimum parameters such as optimum number of channels
and hops are determined.
Numerical Study of Star Anchor Plate Embedded in Cohesive SoilIJERA Editor
Indonesia as an archipelago country has a very long coastline about 90.000 kms. Specifically for shore and offshore, there are many buildings utilizing structures including floating deck, mooring dolphin, offshore platforms etc. Those requires a solution to maintain the stability of the structures due to the vertical movement of tides and horizontal movement of currents, wind and waves. To maintain the stability due to buoyant force, structure of anchors are needed. Various types of the anchor have been widely used such as drag, helical, anchor plate circular shape and square. This study aims to do the development of new modifications of a plate anchor type star with 4 leaves with an area of a fixed and diameter equivalent different on any variations. Ultimate pullout capacity was obtained by using numerical geomechanics analysis within finite difference method. A perfectly plastic soil model was used with a tresca yield criterion. Results are presented including break-out factors based on various anchor shapes and embedment depth. Our findings are also compared with previous numerical and empirical solutions.
Implementation of Secured Car Parking Management System Using Verilog HDLIJERA Editor
Present days usage of motor vehicles are increased day by day, it causes the pollution, traffic congestion and parking place problems. In this paper we proposed a secured car parking management system using Verilog HDL. This system has two main modules Module-1: Slot identification for parking and LCD display screens, Module-2: Security indicator will provide security to the car, if unauthorized person want to vacant the car. These modules are modeled in Verilog HDL and implemented on FPGA.
Automatic Selection of Open Source Multimedia Softwares Using Error Back-Prop...IJERA Editor
Open source opens a new era to provide license of the software for the user at free of cost which is advantage over paid licensed software. In Multimedia applications there are many versions of software are available and there is a problem for the user to select compatible software for their own system. Most of the time while surfing for software a huge list of software opens in response. The selection of particular software which is pretty suitable for the system from a real big list is the biggest challenge that is faced by the users. This work has been done that focuses on the existing open source software that are widely used and to design an automatic system for selection of particular open source software according to the compatibility of users own system. In this work, error back-propagation based neural network is designed in MATLAB for automatic selection of open source software. The system provides the open source software name after taking the information from user. Regression coefficient of 0.93877 is obtained and the results shown are up to the mark and can be utilized for the fast and effective software search.
BER Performance of OFDM-QAM over AWGN and RICAIN Channels Using Error Correct...IJERA Editor
In this paper, the performance of OFDM - QAM system by using error correcting codes (Convolutional, Reed Solomon and Interleaving) schemes that are used to encode the data stream in wireless communications using AWGN and RICIAN channels has been reported here. OFDM is presented for wireless communications we curing basic OFDM and affined modulations, as well as techniques to improve the performance of OFDM for wireless communications. Various simulations are performed to detect the best BER performance of each of the QAM system; OFDM-QAM and OFDM-QAM with Error Correction and to use the best outcomes to model the OFDM-QAM, Their effect of improving the total BER can be noticed due to the benefits of OFDM-QAM with correcting codes.
An Application of Green Quality Function Deployment to Designing an Air Condi...IJERA Editor
The paper tackles a systematic and operational approach to Green Quality Function Deployment (GQFD), a customer oriented survey based quality management system with regular improvement in product development. GQFD shows balance between product development and environmental protection. GQFD is not used to determine their attributes and their levels. GQFD captures what product developers “think” would best satisfy customer needs considering Environmental factor. This research used Air Conditioner as a case study for implementation of GQFD. In the design of a new Air Conditioner, apply GQFD to find out the most important parameter and functions from customer point of view and then find out Technical Characteristics. These important parameters are then put into house of quality and make relation matrix between voice of customer and Technical Characteristics. From the result of QFD applied to Air Conditioner are short out the parameter which are require modification according to voice of customer and the result has used for new design.
Performance of Light-Weight Concrete with Plastic AggregateIJERA Editor
This study is intended to explore the suitability of recycled plastics (high density polyethylene) as coarse aggregate in concrete by conducting various tests like workability by slump test, compressive strength of cube and cylinder, splitting tensile strength test of cylinder, flexural strength of R.C.C as well as P.CC. beams to determine the properties and behaviour in concrete. Effect of replacement of coarse aggregate with various percentages (0% to 40%) of plastic aggregate on behaviour of concrete was experimentally investigated and the optimum replacement of coarse aggregate was found out. The results showed that the addition of plastic aggregate to the concrete mixture improved the properties of the resultant mix.
Summary of fracture mechanics problems analysis method in ABAQUSIJERA Editor
Fracture mechanics is the study of the strength of the materials or structures with crack and crack propagation regularity of a discipline. There are a lot of analysis function of ABAQUS, including fracture analysis. ABAQUS is very easy to use and easy to establish a model of the complicated problem. In order to effectively study of strong discontinuity problems such as crack, provides two methods of simulating the problem of cracks of ABAQUS. This paper describes the two methods respectively, and compare two methods.
Cyclic Heating Effect on Hardness of AluminumIJERA Editor
Presented work discusses research results concerning the effect of the heat treatment process. Thermal fatigue which expresses repeated heating and cooling processes affect the ductility or the brittleness of the material. In this research 70 specimens of aluminum (2 mm thickness, 85 mm length, 32 mm width) are subjected to thermal fatigue at different conditions. Heating temperatures; Th = 100, 300 and 500 ° C. Number of repeated cycles; N =1 to 100. Results are evaluated then compared to each other and to that of specimens without subjected to thermal fatigue.
The present research work deals is to model new fore wheel bearing of agricultural machine used for ploughing which fail in regular usage. This bearing takes three formulations. They are bearing through Material Change Break Down Analysis The design is done in CATIA and Break Even Analysis is done in ANSYS. And find which one among the Bearing through Design or Bearing through Material Change is solution for the problem aimed for. Break Down Analysis is done in each of the cases to find the maximum forces to be applied on the bearings to get the maximum load that can be bared by the bearings. The objective of our project is to find the solution for the regular failure of bearings of machine through different material. Here we are using three materials i.e. steel, tungsten, zinc
Windows used in FIR Filters optimized for Far-side Stop band Attenuation (FSA...IJERA Editor
It has been proposed that the Exponential window provides better side-lobe roll-off ratio than Kaiser window
which is very useful for some applications such as beam forming, filter design, and speech processing. In this
paper the second application i.e. design of digital nonrecursive Finite Impulse Response (FIR) filter by using
Exponential window is proposed. The far-end stopband attenuation is most significant parameter when the
signal to be filtered has great concentration of spectral energy. The filter should be designed in such a way so
that it can provide better far-end stopband attenuation (amplitude of last ripple in stopband). Digital FIR filter
designed by Kaiser window has a better far-end stopband attenuation than filter designed by the other previously
well known adjustable windows such as Dolph-Chebyshev and aramaki, which are special cases of
Ultraspherical windows, but obtaining a digital filter which performs higher far-end stopband attenuation than
Kaiser window will be useful. In this paper, the design of nonrecursive digital FIR filter has been proposed by
using Exponential window. It provides better far-end stopband attenuation than filter designed by well known
Kaiser window, which is the advantage of filter designed by Exponential window. The proposed schemes were
simulated on commercially available software and the results show the close agreement with proposed theory.
Smart Prediction Of Surface Finishing Quality Of En-8 Work Piece By Ann ModelIJERA Editor
Turning is a material removal process a subtractive form of machining which is used to create parts of circular
or rotational form of desired geometry/shape by removing unwanted material. Accuracy of any process depends
on involvement of operational variables. The operating parameters that contribute to turning process are Cutting
speed, Depth of cut, Feed rate. Vibrations, tool life, tool wear, surface finish and cutting forces etc are also in
direct relation with values selected for process parameters. So to improve the efficiency of process and quality
of the product it is necessary to control the process parameters. We have considered surface roughness the
parameters with main focus as it dictates the aesthetics and sometimes ergonomical characteristics of the
product. In this work a neural network is created using feed forward back propagation technique for simulation
of the process using the Matlab Neural network toolbox. So with assurance of accuracy of the predictive
capabilities of the neural network it was then used for optimization.
A Novel Wideband Circularly Polarized Antenna for Worldwide UHF Band RFID Rea...IJERA Editor
This paper presents A Novel Wideband Circularly Polarized Antenna for Worldwide UHF Band RFID Reader
Applications with simple, compact structure. An air-substrate truncated patch antenna is used to achieve the
circularly polarized characteristic. The impedance and AR bandwidth of proposed antenna are 840-960 MHz
(VSWR less than 1.5) and (AR less than 3), respectively. Proposed antenna has a good radiation performance
with gain more than 8 dB. And it is a good choice for UHF RFID applications.
Synthesis, Electrical and Optical Properties of Nickel Sulphate Hexa Hydrate ...IJERA Editor
L-Arginine doped Nickel SulphateHexa Hydrate (NSH) single crystalswere grown by slow evaporation
techniquefor different molar concentrations, viz., (0.2 to 1 mole% in steps of 0.2).The grown crystals were
subjected to various studies.XRD data were collected from powder samples of the crystals.ACelectrical
measurementswerecarriedoutatvarioustemperaturesrangingfrom40-750C. Resultsindicate anincrease
oftheelectricalparameterswiththeincreaseoftemperature.The dielectric value suggests that the L-Arginine doped
NSH single crystal is good for microelectronic application. The UV-Vis-NIR spectral studies were performed to
analyze the optical absorption of the grown crystals in the range 200 – 1100nm. Results obtained were
presented.
Influence of Different Parameters on Heat Pipe PerformanceIJERA Editor
In electrical and electronic industry due to miniaturization of electronic components heat density increases
which, in turns increases the heat flux inside it. Scientist and many researchers are doing lot of work in this field
for thermal management of devices. Heat pipe is a device that is used in electronic circuit (micro and power
electronics), spacecraft & electrical components for cooling purpose. It is based on the principle of evaporation
and condensation of working fluid. Heat pipe made up of three main parts are evaporator, adiabatic and
condenser sections. In this working fluid vaporise at evaporator and transfers heat to condenser by adiabatic
section where heat release to surrounding. Vapour flows possible from evaporator to condenser section due to
vapour pressure difference exist between them. Use of heat pipe material, type of working fluid & its property,
wick structure, orientation, filled ratio, operating condition, dimensions of pipe has a prominent effect on heat
pipe performance. Variation of these parameters for minimum thermal resistance gives better performance.
Antagonism of lactic acid bacteria against pathogenic agents not related to g...IJERA Editor
Oar researchhas provedthat lactic acid bacteria possess the wide spectrum of antagonistic activity. They inhibit the
growth of not only agents of intestinal infections but also agents ofdiseases not related to gastrointestinal tract.
Delay Optimization of Low Power Reversible Gate using MOS Transistor Level de...IJERA Editor
In Semiconductor industry has witnessed and explosive growth of integration of sophisticated multimedia base
application onto mobile electronic gadget since the last decade. The critical concern in this aspect is to reduce the
power consumption beyond a certain range of operating frequency. An important factor in the design of VLSI
circuits is the choices of reversible logic. Basically conventionally digital circuits have been implemented using
the logic gates, which were irreversible in nature only NOT gate are reversible. These irreversible gates produce
energy loss due to the information bits lost during the operation information loss occurs because the total number
of output signals generated is less than total number of input signals applied. In reversible if the input vector can
be uniquely recovered from the output vector and if there is a one to one correspondence between its input and
output logic. This paper present a new representation of existing reversible gate in MOS transistor. The MOS
transistor designing using a gate diffusion input. Those new representation of MOS transistor has a hoping future
in design of low power consumption circuits and high speed application.
TNM Method Results Compared with Finite Element Analysis for a 30 KW SCIM MotorIJERA Editor
The Thermal network model (TNM) of ten node 37 thermal resistances is considered as the highly detailed one
for thermal distribution of all the TNM models. This model is reported to be the one that can take care of most
of the complexities in geometry and estimation of convective heat transfer coefficients. Results obtained for the
30 KW motor using the above TNM model have been compared with that of Finite element Analysis using
ANSYS. Listing of the MATLAB programs is presented as annexure.
REVIEW OF FLOW DISTRIBUTION NETWORK ANALYSIS FOR DISCHARGE SIDE OF CENTRIFUGA...ijiert bestjournal
A computational fluid dynamics (CFD) analysis has been conducted to find the pressure losses for dividing and combining fluid flow through a junction of discharge system. Simulations are performed for a range of flow ratios and equations are developed for pressure loss coefficients at junctions. A mathematical model based on s uccessive approximations then would be employed to estimate the pressure losses. The proposed CFD based strategy can be used for the analysis of all the three pipe branches of s ome diameter are selected along with equal length so that only the effect of bend angle can be st udied. The effect of bend angle,pipe diameter,pipe length,reynolds number on the resistan ce coefficient is studied. The software used is CATIA for modeling and ANSYS fluent for analysis purpose.
FLOW DISTRIBUTION NETWORK ANALYSIS FOR DISCHARGE SIDE OF CENTRIFUGAL PUMPijiert bestjournal
A computational fluid dynamics (CFD) analysis has been conducted to f ind the pressure losses for dividing and combining fluid flow through a junction of discharge system. Si mulations are performed for a range of flow ratios and equations are developed for pressure loss coeff icients at junctions. A mathematical model based on successive approximations then would be employed to estim ate the pressure losses. The proposed CFD based strategy can be used for the analysis of all the thr ee pipe branches of some diameter are selected along with equal length so that only the effect of bend angle can be studied. The effect of bend angle,pipe diameter,pipe length,Reynolds number on the resistance coeffi cient is studied. The software used is CATIA for modeling and ANSYS fluent for analysis purpose.
A REVIEW ON IMPROVEMENT OF EFFICIENCY OF CENTRIFUGAL PUMP THROUGH MODIFICATIO...ijiert bestjournal
The paper reviews the literature available on the i mprovement of efficiency of centrifugal pump through modification in suction manifolds. The paper discusses the available material of performance improvement through various paramete rs and mainly focuses on the research related to manifold modifications.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
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
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
Cavitation Effects in Centrifugal Pumps- A ReviewIJERA Editor
Cavitation is one of the most challenging fluid flow abnormalities leading to detrimental effects on both the
centrifugal pump flow behaviors and physical characteristics. Centrifugal pumps’ most low pressure zones are the
first cavitation victims, where cavitation manifests itself in form of pitting on the pump internal solid walls,
accompanied by noise and vibration, all leading to the pump hydraulic performance degradation. In the present
article, a general description of centrifugal pump performance and related parameters is presented. Based on the
literature survey, some light were shed on fundamental cavitation features; where different aspects relating to
cavitation in centrifugal pumps were briefly discussed.
Numerical analysis for two phase flow distribution headers in heat exchangerseSAT Journals
Abstract A flow header having number of multiple small branch pipes are commonly used in heat exchangers and boilers. In beginning the headers were designed based on the assumption that the fluid distribute equally to all lateral pipes. In practical situation the flow is not uniform and equal in all lateral pipes. Mal distribution of flow in heat exchangers significantly affects their performance. Non-uniform flow distribution from header to the branch pipes in a flow system will lead to 25% decrease in effectiveness of a cross flow heat exchanger. Mal distribution of flow in the header is influenced by the geometric parameters and operating conditions of the header. In this work the flow distribution among the branch pipes of dividing flow header system is analyzed for two phase flow condition. In the two phase flow condition, the effect of change in geometric cross sectional shape of the header (circular, square), inlet flow velocities are varied to find the flow mal distribution through the lateral pipes are investigated with the use of Computational Fluid Dynamics software. Keywords: circular, square headers and Computational Fluid Dynamics software. (CFD)
Dynamic Stability of Zaghloul Drainage Pumping Station, Kafr El Shiekh, EgyptIJERA Editor
Zaghloul Pumping Station located at El-Moheet drainage in Kafr El Sheikh Governorate. The station consists of four axial pumping units. The operating system depends on running not more than three pumping units. The old station is replaced by new one and the old sump is reused with some modifications. Each pump takes 20 second to start and takes 300 second to reach steady state. Activation more than two units lead to decrease the suction water level, disturbance of velocity distribution in suction intake and increase vibration and noise levels. The disturbance in velocity distribution generates dynamic instability of pumping units which leads to failure, damage and other operation and maintenance difficulties. Field measurements and numerical simulation were done to investigate dynamic stability of the station. The Solid Works flow simulation software, Computational Fluid Dynamics (CFD) is used to simulate the flow conditions at different water levels to predict the hydraulic problem at the suction side. The field measurements are used to investigate the dynamic problem. Measurements are used to measure pump flow rate, pump head and vibration levels. The (MVP2C OneproD/ ACOEM) two channel vibration analyzer and data collector was used to prepare dynamic balancing for each unit with different weights. In general, the results indicated that with the decrease of water level; approach velocity increases, swirl and vortices induce vibrations and excessive bearing loads. From simulation results the geometry of suction intake is proper for running three parallel axial flow pumps with the designed flow rate. The input data to simulation model were taken from the filed measurements and this data is validating to simulation model. The dynamic balancing as a solution leads to reduce vibration level and save bearing life. It is very important to investigate the dynamic stability and check the dynamic balancing for pumping units at the primary operation of the new stations as mentioned in the bidding
Butterfly valves are widely used in hydro power plants to regulate and control the flow
through hydraulic turbines. That’s why it is important to design the valve in such a way that it can give
best performance so that optimum efficiency can be achieved in hydraulic power plants. Conventionally
that the models of large size valves are straight in the laboratory to determine their performance
characteristics. This is a time consuming and costly process. High computing facility along with the use
of numerical techniques can give the solution to any fluid flow problem in a lesser time. In this research
work flow analysis through butterfly valve with aspect ratio 1/3 has been performed using
computational software. For modelling the valve ICEM CFD 12 has been used. Valve characteristics
such as flow coefficient and head loss coefficient has been determined using CFX 12 for different valve
opening angle as 30°,60°,75°, and 90° (taking 90°as full opening of the valve) for incompressible fluid.
Value of head loss coefficient obtained from numerical analysis has been compared with the
experimental results.
Numerical Investigation of Flow Field Behaviour and Pressure Fluctuations wit...Mustansiriyah University
this present work, CFD numerical method is applied to analyses the flow field in
an axial flow pump qualitative and quantitative analyses. Qualitative analysis for these
parameters comprise static pressure variations, dynamic pressure variations, velocity magnitude,
turbulent kinetic energy, shear stress. Quantitative analysis including the pressure fluctuations in
frequency domain analysis under different operation conditions. Also, sliding mesh method and
turbulence model type k- epsilon are used. Various monitoring points are stalled in order to
analyses pressure fluctuation mechanism in the impeller blade. The numerical results revealed
that the flow field for pressure and velocity are increase start from the suction side of the pump
to discharge side. Also, the results found that the high pressure occurs at the discharge side
along the axial direction of the impeller. The maximum value of pressure fluctuations is
occurred at tip blade region due to high interaction flow at this particular area. Moreover, the
pressure decreases as flow rate in the pump increases. Additionally, the results shown that the
pressure fluctuations have four peaks and four valleys the similar impeller blades number.
Furthermore, there are different positive and negative pressure regions, the negative pressure
area occurs due to lower pressure zone at inlet impeller area and hence which can lead to cause
occurrence of cavitation in this specific area. The current numerical demonstration results can
help the researches for further axial flow pump design.
COMPUTATIONAL ANALYSIS OF FLUID FLOW THROUGH ROTATING VANELESS DIFFUSERIjripublishers Ijri
The main objective of the work is to analyze the behavior of the fluid flow through a rotating vaneless diffuser,
flow near wall conditions, performance characteristics and means to reduce the flow losses in a centrifugal
compressor. The project presents a numerical procedure to investigate the pressure distortion at
exit flow of impeller and flow fields around impeller blade and to validate computational results against experimental
data with various models. In rotating vane less diffuser, there are various concepts. The concept
of blade cut back is to be employed in back ward curved impeller to obtain the rotating vaneless diffuser,
which rotates with the speed of the centrifugal impeller and the performance parameters is to be compared
with the static vane less diffuser.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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Flow analysis of centrifugal pump using CFX solver and remedies for cavitation mitigation
1. Dr. G. Rambabu et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 5, Issue 7, (Part - 3) July 2015, pp.52-58
www.ijera.com 52 | P a g e
Flow analysis of centrifugal pump using CFX solver and remedies
for cavitation mitigation
Dr. G. Rambabu*, S. Sampath** G. Karthik*** S. Siva Teja****
*(Department of Mechanical Engineering, Andhra University College of Engineering, A.U.C.E(A),
Visakhapatnam-530003
** (Department of Mechanical Engineering, Andhra University College of Engineering, A.U.C.E(A),
Visakhapatnam-530003
***Department of Mechanical Engineering, Andhra University College of Engineering, A.U.C.E(A),
Visakhapatnam-530003
*****Department of Mechanical Engineering, Andhra University College of Engineering, A.U.C.E(A),
Visakhapatnam-530003
ABSTRACT
In this scholarly thesis pertinent to the working of centrifugal pump, a CFD solver namely CFX is employed in
order to simulate fluid flow characteristics with well-defined constraints and boundary conditions defining the
problem. Stringent solid model is meticulously prepared encompassing the present day usage and constructional
features of a centrifugal pump and is constrained with various boundary conditions having fixed domain in order
to evaluate plots and results. To spearhead and facilitate this analysis program a numerical approximation tool
with high degree of convergence rate called ANSYS 15.0 software is used. The ASNYS software avoids tedious
calculations presumably impending in the design procedure and uses ultimate numerical tool to approximate the
solution of the partial differential equations associated with continuity, momentum and energy phases of a flow
problem in a 3-D model. This exquisite feature of ANSYS enables designer to optimize the design procedure in
an iterative manner based on the final plots of post-processing phase. In addition, the scholarly writing also
constitutes the appraisal of the most debilitating and painstaking problem retarding the efficiency of the
centrifugal pump known as cavitation. Possible remedies for overcoming this problem will be indirectly inferred
from the various plots and figures derived from the post-processing phase of the design process.
Keywords - Cavitation, NPSH, CFD.
I. Introduction
(What is cavitation?)
Cavitation is the formation and subsequent
collapse or implosion of vapor bubbles inside the
pump. It occurs because the absolute pressure of the
liquid drops below the liquid's vapor pressure. When
vapor bubbles collapse with enough frequency, it
sounds like marbles and rocks are moving through
the pump. If larger number of vapor particles
accumulate they become irresistible and causes
indentation on the surface encompassing the pump
leading to pitting action. This pitting action corrodes
the metal leading to noisy operation of the pump and
sometimes leads to massive explosion. Cavitation is
a painstaking problem in today's commercial usage
of pump and must be avoided to avert any
retardation in the functioning of the pump.
Cavitation is bound to lower the efficiency of the
pump. If the pump operates under cavitating
conditions for rough times, the following can occur:
Pitting marks on the impeller blades and on the
internal volute casing of the pump.
Premature bearing failure.
Shaft breakage and other fatigue failures in the
pump.
Pre-mature mechanical failure.
Factors perpetrating cavitation in a pump:
Fall of absolute pressure at the suction nozzle
below the saturation vapor pressure
corresponding to ambient temperature of the
water.
An increase in the temperature of the pumped
liquid.
An increase in the velocity or flow of the fluid.
Separation and reduction of the flow due to a
change in the viscosity of the liquid.
Undesirable flow conditions caused by
obstructions or sharp elbows in the suction
piping.
The pump is inadequate for the system.
RESEARCH ARTICLE OPEN ACCESS
2. Dr. G. Rambabu et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 5, Issue 7, (Part - 3) July 2015, pp.52-58
www.ijera.com 53 | P a g e
II. Estimation and prediction of cavitation
A powerful tool to access the demerits of a
centrifugal pump is the net positive suction head
denoted as NPSH. This tool helps in the evaluation
of the toughest pain staking problem entangled in the
operating condition of the centrifugal pump. Net
positive suction head is defined as the minimum
head required at any point of the centrifugal pump to
avoid cavitation. It is the energy in the liquid
required to overcome the friction losses from the
suction nozzle to the eye of the impeller without
causing vaporisation. It is a characteristic of the
pump and is indicated on the pump's curve. It varies
by design, size, and the operating conditions. It is
determined by a lift test, producing a negative
pressure in inches of mercury and converted into
feet of required NPSH. According, to the standards
of hydraulic institute, a suction lift test is performed
on the pump and the pressure in the suction vessel is
lowered to the point where the pump suffers a 3%
loss in the total head. This point is called the NPSHr
of the pump.
Generally, this net positive suction head theory is
only applicable to the eye and suction of the impeller
only because the vapor pressure at running
conditions is highly capricious due to the advent of
the frictional head loss and its conversion into heat
energy leading to a rise in the temperature of the
liquid. This ultimately decreases the vapor pressure.
Moreover, the vapor pressure distribution is not
stagnant throughout the impeller plane and thus
NPSH is not applicable to the total portion of the
pump.
+ (1)
where,
p1- absolute pressure at inlet.
pv1- vapor absolute pressure.
C- velocity at inlet.
p- density of liquid.
g- acceleration due to gravity.
and moreover,
(2)
where, NPSHr- net positive suction head required.
NPSHa- net positive suction head available.
Following are the exquisite features of NPSH:
Prediction of cavitation and its evaluation.
Determining the necessary NPSH inorder to
overcome cavitation at all working conditions of
the pump.
Evaluating the required NPSH by adding 3 feet
head to the available NPSH.
III. What is CFD?
Computational fluid dynamics has certainly
come of age in industrial applications and academic
research. In the beginning, this popular field of
study, usually referred to by its acronym CFD, was
only known in the high-technology engineering
areas of aeronautics and astronautics, but now it is
becoming a rapidly adopted methodology for solving
complex problems in modem engineering practice.
CFD, which is derived from the disciplines of fluid
mechanics and heat transfer, is also finding its way
into important uncharted areas, especially in process,
chemical, civil, and environmental engineering.
Construction of new and improved system designs
and optimization carried out on existing equipment
through computational simulations are resulting in
enhanced efficiency and lower operating costs. With
the concerns about global warming and the world’s
increasing population, engineers in power-
generation industries are heavily relying on CFD to
reduce development and retrofitting costs. These
computational studies are currently being performed
to address pertinent issues relating to technologies
for clean and renewable power as well as for
meeting strict regulatory challenges, such as
emissions control and substantial reduction of
environmental pollutants. The fundamental basis of
almost all CFD problems are the Navier–Stokes
equations, which define any single-phase (gas or
liquid, but not both) fluid flow. These equations can
be simplified by removing terms describing viscous
actions to yield the Euler equations. Further
simplification, by removing terms describing
vorticity yields the full potential equations. Finally,
for small perturbations in subsonic and supersonic
flows (not transonic or hypersonic) these equations
can be linearized to yield the linearized potential
equations.
3.1 Computational fluid dynamics can be
summarized as follows
An approximate numerical tool used to solve 3-
D fluid flow problems whose solution has
greater degree of convergence to the exact
solution.
An analyzer in optimizing the design procedure
by constructing its own contingent objective
function which is governed by some typical
fluid flow parameters.
A bundle of database helpful in simulating the
flow characteristics of any fluid described in it.
An authentic tool which avoids the tedious,
long-winded calculations in determining the
exact solution of various partial differential
equations for a given boundary condition
stipulated by the user.
3.2 Application of CFD
In, designing Aircrafts and its aerofoiled shape
wings, tail etc for given Mach number and the
type of flow associated with it which may be
sonic, sub-sonic, super-sonic.
For, designing pumps and turbines by
simulating and imparting the desired fluid flow
conditions and characteristics.
3. Dr. G. Rambabu et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 5, Issue 7, (Part - 3) July 2015, pp.52-58
www.ijera.com 54 | P a g e
In Estimation and optimization of a design
procedure pertinent to various fluid flow
devices and machines.
For designing and analyzing of the finned
structure encapsulating the motor cycle engine.
In the appraisal and analysis of complex
structures by integrating with other simulation
analysis programs aided by the ANSYS
SOFTWARE.
3.3 CFD approach and problem solving
methodology
There are generally three phases involved in the
problem solving strategy adopted by any analysis
problem. Each phase of this methodology is a
rudimentary and an unavoidable procedure for
having the desired outcome of best simulation
results predicted by the software before-hand
without an inclination to the destructive testing
analysis. The following are the three phases
associated with any ANSYS problem:
o Pre-Processing Phase:
The geometry (physical bounds) of the problem
is defined.
The volume occupied by the fluid is divided
into discrete cells (the mesh). The mesh may be
uniform or non-uniform.
The physical modeling is defined- for example,
the equations of motion + enthalpy + radiation +
species conservation.
Boundary conditions are devised. This involves
specifying the fluid behavior and its properties
at the boundaries of the problem. For transient
problems, the initial conditions are also defined.
o Processing Phase:
The simulation is started and the equations are
solved iteratively as a steady-state or transient.
This phase is totally dependent upon the
processing speed and type of processor
employed in the work station.
o Post-Processing Phase:
Finally a postprocessor is used for the analysis
and visualization of the resulting solution.
This phase usually constitutes various plots and
graphs contingent to the fluid flow problem
being analyzed.
The solver's analysis comes under the post
processing phase of the CAD/CAM procedure after
completing the Geometric modeling and physics
definition of the problem. Actually, CFD is a
misnomer for the computing solver in analyzing
various fluid flow problems. But the actual tool or
solver used for computing fluid flow problems is the
ANSYS SOFTWARE and its embedded tools.
ANSYS is an integrated software gleamed from
various sources, database for performing wide range
analysis, optimization of design which not only
include fluid flow analysis but also convoluted
problems associated with Civil structural analysis,
Heat flow analysis, Dynamic analysis, Kinematic
analysis, Electromagnetic problems etc. Various
solvers incorporated in ANSYS for fluid analysis
are:
Fluid Flow- Blow Molding (Polyflow)
Fluid Flow- Extrusion (Polyflow)
Fluid Flow (CFX)
Fluid Flow (Polyflow)
IV. Pre-processing phase:
Pre-Processing phase as described before deals
with Geometric modeling, Meshing- mesh
generation, mesh gradation, density, and lastly
comes in defining the physics of the given fluid flow
problem. The pre-processing phase serves as back
bone of CAD/CAM processes and helps in providing
better visual interface to the user integrating the
graphics system along with the various periphery
devices present in the work station. A typical
workstation defining geometric modeling and mesh
generation constitutes the following items:
Graphics system and software.
Periphery devices like-plotters, mouse,
keyboard, monitor, digitizer, printers etc.
CATIA software.
The pre-processing stage constitutes the crux of all
the three phases describing the 3-D geometric model
of the design process which helps in simulating the
physics in the analysis stage. In addition it also helps
in gridding the complex problem to a more facile
one constituting the replica of the same element for
quick generation of results. The pre-processing stage
or phase comprises the following three indispensible
elements:
Geometric modeling
Mesh generation
Physics definition
The final facade of the drawing encompassing
present day constructional features of a centrifugal
pump is shown in the figure 4.1. The model includes
an inlet, an outlet or discharge, impeller and a casing
circumventing it and is made keeping in mind the
present day constructional features of a centrifugal
pump.
Fig 4.1
4. Dr. G. Rambabu et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 5, Issue 7, (Part - 3) July 2015, pp.52-58
www.ijera.com 55 | P a g e
V. Processing phase:
Usually, the finite element approach comes
under processing phase of the design procedure
where the actual physics and boundary conditions
are devised and analysis is carried giving adequate
results. However, present day ANSYS software's
simulating analysis program are capable of handling
all the three phases of the design procedure namely-
preprocessing, processing and post processing where
intricate 3-D models are drawn and sketched with
greater flexibility. Adding, meshing and grid
generation is also incorporated in the software.
5.1 Steps in finite-element procedures
Most generalized procedure for carrying out FEA for
any analysis problem is as follows:
Procedure 1:Discretization Divide the object of
analysis into a finite number of finite elements.
Procedure 2:Selection of the interpolation
function Select the element type or the
interpolation function which approximates
displacements and strains in each finite
element.
Procedure 3:Derivation of element stiffness
matrices Determine the element stiffness
matrix which relates forces and displacements
in each element.
Procedure 4:Assembly of stiffness matrices into
the global stiffness matrix Assemble the element
stiffness matrices into the global stiffness matrix
which relates forces and displacements in the
whole elastic body to be analyzed.
Procedure 5:Rearrangement of the global
stiffness matrix Substitute prescribed applied
forces (mechanical boundary conditions) and
displacements (geometrical boundary
conditions) into the global stiffness matrix, and
rearrange the matrix by collecting unknown
variables for forces and displacements, say in
the left-hand side, and known values of the
forces and displacements in the right-hand side
in order to set up simultaneous equations.
Procedure 6:Derivation of unknown forces and
displacements Solve the simultaneous equations
set up in Procedure 5 above to solve the
unknown variables for forces and
displacements. The solutions for unknown
forces are reaction forces and those for
unknown displacements are deformations of the
elastic body of interest for given geometrical
and mechanical boundary conditions,
respectively.
Procedure 7:Computation of strains and stresses
Compute the strains and stresses from the
displacements obtained in Procedure 6
VI. Post-processing phase:
The solution, results and plots obtained in the
ANSYS software has great significance for the pre-
determined path chosen for analysis. Validation of
the results can be done by Rapid prototyping before
actual advent of the designed product into the
market. In case of a civil structural problem, element
strains and stresses are the final outcomes of the
analysis along with typical plots depicting the stress
distribution along the whole continuum. The results
and plots obtained in the post-processing phase
depends upon the following factors:
Number of nodes, elements
Type of element chosen
Mesh density and mesh gradation
Number of iterations
6.1 Significance of the plots
6.1.1 Absolute pressure rotation plot (impeller with
casing)
The following adjacent plot relates the absolute
pressure distribution along the domain of the
centrifugal pump. The red portion depicts the area of
high pressure prone region along the volute casing of
the centrifugal pump and the navy blue portion
entails the region of low absolute pressure.
Fig 6.1.1 a
Obviously, it is true that the eye and the inlet of the
impeller i.e the suction region has low pressure
which is to be pressurized to a high pressure zone at
the discharge at outlet. The absolute pressure chart
maps the regions of the lowest pressure plots inorder
to insinuate the presence of saturated vapor pressure
at the eye of the impeller. This will serve as an
indication of the cavitation in a pump. The areas of
light blue also represents the scarcity of NPSH
available at that point.
6.1.2 Pressure rotation plot (impeller pad only)
This lucidly depicts how pressure builds up along
the plane of the impeller during the running
conditions of the pump. The light blue portion
encompassing some part of the eye is more prone to
low absolute and have high risks of cavitation in
those areas.
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Fig 6.1.2 a
The impeller is given a specific angular speed and
the pressure distribution plane can be observed
clearly. It must be noted that cavitation tendancy
depends greatly upon the speed of the impeller also.
During rotation the outer edge of the impeller vanes
are subjected to hydraullic stresses and muct be
backed up with intricate contours (which is nothing
but the casing) inorder to sustain it.
.6.1.3 Total pressure plot (impeller back portion and
eye)
This plot gives the vulnerable areas of the high
pressure at the interspaces enclosed between the
vanes. The interspaces between vanes close to the
discharge have high tendancy to hydraullic stresses
(red region) during the running condition of the
pump where as the interspaces included by the vanes
at gradually increasing cross section of the casing is
more prone to cavitation if the absolute pressure of
the liquid is below vapor pressure of the liquid at
ambient conditions. To have a better comprehension
of the total pressure plot a perspective snapshot is
Fig 6.1.3a
taken which is schematically depicted in the
folowing adjacent Fig 6.1.3 b. The hazy red portion
Fig 6.1.3 b
represents the casing encompassing the impeller and
the discharge tube at outlet. The superimposition of
the impeller plane and casing plane gives the above
plot and can be validated as more generic form of
interpretation for judging the centrifugal pump's
performance.
6.1.4 Total pressure outlet
This plot enables the manufacturers to curtail and
evaluate the performance plots of the pump
depending upon the type of application demanded by
the consumer. The difference between the inlet and
outlet absolute pressure head determines the net
Fig 6.1.4 a
effective head developed by the pump at various
speeds and operating suction head. The
superimposition of all the above plots gives the
following plot shown in figure 6.1 e which is used
by the consumer in the manufacturer's catalogue for
choosing a particular type of pump for a given
application. The manufacturer's catalogue constitutes
a scale entailing NPSH for a given speed and
discharge head enabling the customer's to have a
greater overview of the pump's commercial
exploitation.
6.1.5 Vapor superfical velocity
The most exquisite feature of CFX solver of the
ANSYS software is its ability to map and point the
areas of highest vapor velocity due to the cavitation
phenomenon causing pitting action on the casing and
vane material. The vapor velocity flow pattern for a
given speed of the impeller can be easily interpreted
and comprehended. Even though the fluid attains
particular pressure energy at the expense velocity
head, there will always be certain disturbances in the
flow due to the advent of cavitation leading to the
fall of pressure energy. This case is most important
pertinent to water which is making its way out of the
impeller with cavitating conditions. Consequently,
high velocity vapor bubbles start hitting the casing
encompassing the impeller, ensuing pitting action.
The adjacent plot gives the vapor superfical velocity
at cavitating conditions and infers the places likely
to effect greatly by pitting action of the high velocity
vapor bubbles. The velocity of superficial vapor
bubbles greatly depends on the type of casing and
the angular velocity of the impeller. The red- dashed
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lines showcase the regions with high vapor velocity
for a given speed of the impeller.
Fig 6.1.5 a
VII. Conclusion and scope:
There are a number of inferences made from the
plots articulated by the CFD analysis of a centrifugal
pump. Conclusive suppositions are brought down by
contrasting the post-processing plots with different
operating conditions of the centrifugal pump. The
focus should be on resolving cavitation problems
either by increasing the external pressure on the fluid
or decreasing its vapor pressure. The external
pressure could be increased by:
Increasing the pressure at the pump suction
such that the absolute pressure of water at inlet
does not falls below the saturation pressure at
that temperature present in the ambience.
Reducing the energy losses incurring at the eye
of the pump. This can be resolved by using a
frictionless small length suction inlet.
Using a larger pump.
Vapor pressure of the fluid is decreased by:
Lowering the temperature of the fluid.
Changing to a fluid with a lower vapor pressure.
We are witnessing a renaissance of computer
simulation technology in many industrial
applications. This changing landscape is partly
attributable to the rapid evolution of CFD techniques
and models. For example, state-of-the-art models for
simulating complex fluid-mechanics problems, such
as jet flames, buoyant fires, and multi-phase and/or
multi-component flows, are now being progressively
applied, especially through the availability of multi-
purpose commercial CFD computer programs. The
increasing use of these programs in industries makes
clear that very demanding practical problems are
now being analyzed by CFD. With decreasing
hardware costs and rapid computing times, engineers
are increasingly relying on the reliable yet easy-to-
use CFD tools to deliver accurate results, as
described in the examples in the previous sections.
Additionally, significant advances in virtual
technology and electronic reporting are allowing
engineers to swiftly view and interrogate the CFD
predictions and to make necessary assessments and
judgments on a given engineering design. In
industry, CFD will eventually be so entrenched in
the design process that new product development
will evolve toward “zero-prototype engineering.’'
Such a conceptual design approach is not a mere
flight of the imagination, but rather a reality in the
foreseeable future, especially in the automotive
industry. Looking ahead, full-vehicle CFD models
with undershoot climate control, and external
aerodynamics will eventually be assembled into one
comprehensive model to solve and analyze vehicle
designs in hours instead of days. Time-dependent
simulations will be routinely performed to
investigate every possible design aspect. Other
related “co-simulation" areas in ascertaining the
structural integrity as well as the acoustics of the
vehicle will also be computed concurrently with the
CFD models. Engineering judgment will be
consistently exercised on the spot through real-time
assessments of proposed customized design
simulations in selecting the optimum vehicle. In the
area of research, the advances in computational
resources are establishing large eddy simulation
(LES) as the preferred methodology for many tur-
bulence investigations of fundamental fluid-
dynamics problems. Since all real- world flows are
inherently unsteady, LES provides the means of
obtaining such solutions and is gradually replacing
traditional two-equation models in academic
research. The demand for LES modeling is steadily
growing. LES has made significant inroads,
especially in single-phase fluid flows. In combustion
research, LES has also gained much respectability,
particularly in capturing complex flame
characteristics because of its better accommodation
of the unsteadiness of the large-scale turbulence
structure affecting the combustion
VIII. Limitations:
Although much effort has been focused on
developing more robust CFD models to predict
complicated multi-phase physics involving gas-
liquid, gas-solid, liquid-solid, or gas-liquid-solid
flows, LES (large eddy simulation) remains in its
infancy of application to these flow problems.
Instead, two-equation turbulence models are still
very prevalent in accounting for the turbulence
within such flows. LES may be adopted as the
preferred turbulence model for multi-phase flows in
the future but, in the meantime, the immediate need
is to further develop more sophisticated two-
equation turbulence models to resolve these flows.
Based on current computational resources, numerical
calculations performed through LES can be long and
arduous due to the large number of grid nodal points
required for computations. However, the ever-
escalating trend of fast computing will permit such
calculations to be performed more regularly in the
foreseeable future. Also, with the model gradually
moving away from the confines of academic
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research into the industry environment, it is not
entirely surprising that LES will eventually become
a common method for investigating many physical
aspects of practical industrial flows.
8.1 Following are the limitations of CFD analysis in
this project
The rate of convergence to the exact solution of
the partial differential equations is very low
below 100 iterations and high speed computers
are required to enhance and interpret iterations
above 100. Generally, best solution arrives at
400-500 iterations and greatly depends upon the
type of problem chosen.
The remedies suggested for cavitation of the
centrifugal pump relents on the operational
working conditions of the pump and no
constructional optimization details is disclosed
by the project thesis.
Cavitation analysis made in this project is
confined to both on-load and off-load phases.
However, it is difficult to infer conclusions
from the on-load characteristics because it is
contingent upon various factors like type of the
casing material, vane material, thermal
properties of the vanes and casing adhering to
frictional head loss resulting in highly
capricious NPSHr (net positive suction head
required).
No methods or remedies are studied regarding
the erroneous vibrations and noise emanated
from the working of a centrifugal pump.
IX. Nomenclature:
CFD- computational fluid dynamics.
NPSH- net positive suction head.
NPSHa- net postive suction head available.
NPSHr- net positive suction head rquired.
p1- absolute pressure at inlet.
pv1- vapor absolute pressure.
C- velocity at inlet.
p- density of liquid.
g- acceleration due to gravity.
X. Acknowledgment:
This project thesis and documentation is done
with grim determination under strict tutelage of our
mentor Dr. G. Rambabu and any claims raised by
the third party for a facsimile unauthenticated copy
is merely a coincidence and will be disavowed by
the members of the batch. In addition, any attempts
for emulating this thesis content and analysis will
also be condemned and pertinent legal action will be
sued against the third party. Finally we acknowledge
the contribution of all those who have helped us
directly or indirectly with their good wishes and
constructive criticism which lead to successful
completion of our Project.
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