- The document discusses external aerodynamic analysis of heavy commercial vehicles (HCVs) using computational fluid dynamics (CFD) simulation and wind tunnel testing.
- It aims to study the coefficient of drag of HCVs with different shapes and heights of wind deflectors. Three-dimensional models of the HCV are created in CATIA and analyzed in ANSYS-CFX to compare flow patterns and drag forces.
- The simulation results will be validated through subsonic wind tunnel testing of scaled physical models, which will also utilize smoke flow visualization and surface pressure distribution measurements.
Drag Reduction of Front Wing of an F1 Car using Adjoint Optimisationyasirmaliq
The Project Poster summarizes the aims and objectives of the Final Year Dissertation. The project starts with a detailed study on the parameters that tend to affect the performance of front wings of an F1 car and goes through designing the front wings(3) with endplates and wheel, meshing it, solving/analysing the flow and finally optimising the selected geometry using Fluent Adjoint Solver for efficient performance.
Adjoint optimisation technique is used to achieve optimal performance from the front wings. It's the most successful shape optimisation method as it's independent of the number of design variables exponentially reducing computational time and cost. The emphasis has been put on optimising the shape of the front wings using the Adjoint method as it’s the most efficient and computationally inexpensive method for design optimisation. The approach towards shape optimisation is downforce constrained drag minimization as it would result in keeping a constraint on downforce and reducing the drag at the same time, thus producing optima for a given downforce/drag value.
Drag Reduction of Front Wing of an F1 Car using Adjoint Optimisationyasirmaliq
The Project Poster summarizes the aims and objectives of the Final Year Dissertation. The project starts with a detailed study on the parameters that tend to affect the performance of front wings of an F1 car and goes through designing the front wings(3) with endplates and wheel, meshing it, solving/analysing the flow and finally optimising the selected geometry using Fluent Adjoint Solver for efficient performance.
Adjoint optimisation technique is used to achieve optimal performance from the front wings. It's the most successful shape optimisation method as it's independent of the number of design variables exponentially reducing computational time and cost. The emphasis has been put on optimising the shape of the front wings using the Adjoint method as it’s the most efficient and computationally inexpensive method for design optimisation. The approach towards shape optimisation is downforce constrained drag minimization as it would result in keeping a constraint on downforce and reducing the drag at the same time, thus producing optima for a given downforce/drag value.
Performance Study of Wind Friction Reduction Attachments for Van Using Comput...IJERA Editor
Road transport is the key factor as it is the major method to connect places through land. Along with wide use of internal combustion engines for this purpose comes the massive consumption of fossil fuels by vehicles. Most of the research today is toward making efficient machines. This paper mainly deals with providing attachments to existing models of vehicle to make it more efficient. An assessment of the impact of aerodynamic drag and its relationship to energy consumption presented. A few models are designed and analysed for reducing drag with the help of Attachments. Solid works is used to model and ANSYS Fluent is used for CFD analysis. The results of Cd of various configuration is analysed, 0.427 being the Cd for conventional Van is reduced to 0.234 for van with front and rear attachment.
CFD Simulation for Flow over Passenger Car Using Tail Plates for Aerodynamic ...IOSR Journals
This work proposes an effective numerical model based on the Computational Fluid Dynamics
(CFD) approach to obtain the flow structure around a passenger car with Tail Plates. The experimental work of
the test vehicle and grid system is constructed by ANSYS-14.0. FLUENT which is the CFD solver & employed in
the present work. In this study, numerical iterations are completed, then after aerodynamic data and detailed
complicated flow structure are visualized.
In the present work, model of generic passenger car has been developed in solid works-10 and
generated the wind tunnel and applied the boundary conditions in ANSYS workbench 14.0 platform then after
testing and simulation has been performed for the evaluation of drag coefficient for passenger car. In another
case, the aerodynamics of the most suitable design of tail plate is introduced and analysedfor the evaluation of
drag coefficient for passenger car. The addition of tail plates results in a reduction of the drag-coefficient
3.87% and lift coefficient 16.62% in head-on wind. Rounding the edges partially reduces drag in head-on wind
but does not bring about the significant improvements in the aerodynamic efficiency of the passenger car with
tail plates, it can be obtained. Hence, the drag force can be reduced by using add on devices on vehicle and fuel
economy, stability of a passenger car can be improved.
SIMULTANEOUS OPTIMIZATION OF SEMIACTIVE QUARTER CAR SUSPENSION PARAMETERS USI...ijmech
In present paper, a methodology is presented related to the optimization of semi-active quarter car model
suspension parameters having three degrees of freedom, subjected to bump type of road excitation.
Influence of primary suspension stiffness, primary suspension damping, secondary suspension stiffness and
secondary suspension damping are studied on the passenger ride comfort, taking root mean square (RMS)
values of passenger seat displacement and settling time into account. Semi-active quarter car model
assembled with magneto-rheological (MR) shock absorber is selected for optimization of suspension
parameters using Taguchi method in combination with Grey relational analysis. Confirmatory results with
simulation run indicates that the optimized results of suspension parameters are helpful in achieving the
best ride comfort to travelling passengers in terms of minimization of passenger seat displacement and
settling time values.
Assessment of Flow Control using Passive Devices around Bluff BodiesAnuragSingh1049
This article presents a review study on the experimental investigation of aerodynamic force on a car like bluff bodies along with the simulations using different turbulence models used in CFD (Computational Fluid Dynamics). The aim of the study is to find a useful method for the better design of a car body. It was observed that combination of wind tunnel experiments and CFD computation can lead to better aerodynamic design. Significant reduction in coefficient of the lift and drag for a car model were found when a more streamlined body design was adopted. Appropriate change in the slant angle for the car body can significantly reduce the fuel consumption. Also, the use of simulations in combination with the experimental observations helps in predicting the flow behavior more accurately.
Assessing the Aerodynamic Performance of a Formula SAE Model by means of CFD ...saeid ghaffari
A simplified race car model is used in this project to analyse the aerodynamic performance of a Formula SAE car by means of CFD simulation. First, the simulation workflow in Star-CCM+ will be demonstrated. Then, before applying volumetric controls and prism-layer mesh refinement to obtain more accurate results, tools to judge solution convergence are introduced.
*the first six pages of this project are presented here. If you are interested to study the rest of this document, please contact me via saeid.ghaffari@studenti.polito.it.
Selection of powertrain for vehicle is depends upon vehicle type & application of vehicle. To achieve performance of vehicle, engine torque at maximum revolutions, Transmission ratio, Axle ratio & tire plays important role. In order to understand vehicle performance in theoretical calculation there should be proper selection of power train aggregates. All these aggregates technically will evaluate the actual vehicle performances. For example, trucks are seldom run at their rated maximum speed. In fact, they are usually operated with engine speed at maximum torque or at the speed where fuel consumption is minimized. In climbing hills, there may be occasions when the engine revolution is raised to its maximum to produce the maximum horsepower; however, the most efficient method of operation is to use the range of engine speed, which maximizes torque. If an engine's speed range, producing maximum torque, is extremely narrow, a slight increase of rpm will cause a substantial loss of power and sign of poor performance characteristic. In other words, engines with high maximum torque and horsepower are not necessarily the most "powerful engine." Factors other than the maximum values of the torque and horsepower must be evaluated in determining the practical performance of engines. Furthermore, a high performance engine must be combined with the correct transmission and differential in order to produce the desired running performance. It is necessary to understand the factors affecting its ease of operations. This Paper tells how to integrate powertrain and judge performance of vehicle according to application and type of vehicle by reading performance curves and calculation
Design modification on Indian Road Vehicles to Reduce Aerodynamic DragIJAEMSJORNAL
Reducing vehicle fuel consumption has become one of the most important issues in recent years. Aerodynamic drag contributes to 50-60% of fuel consumption in trucks on highways. Vehicle aerodynamic performance is mainly determined by drag coefficient, which directly affects engine requirements and fuel consumption. It’s well known that drag changes in a crosswind compared with a condition without a crosswind, and that the change depends on the vehicle shape. Pressure drag, a major drag for trucks as they run at lower speeds is produced by the shape of the object. Therefore, addition of some components can suffice the need. The vehicle has been designed by using Catia and then analysed with CFD. The values are compared and the resultant drag reduction is calculated.
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.
Newly Developed Nonlinear Vehicle Model for an Active Anti-roll Bar SystemjournalBEEI
This paper presents the development of a newly developed nonlinear vehicle model is used in the validation process of the vehicle model. The parameters chosen in a newly developed vehicle model is developed based on CARSIM vehicle model by using non-dominated sorting genetic algorithm version II (NSGA-II) optimization method. The ride comfort and handling performances have been one of the main objective to fulfil the expectation of customers in the vehicle development. Full nonlinear vehicle model which consists of ride, handling and Magic tyre subsystems has been derived and developed in MATLAB/Simulink. Then, optimum values of the full nonlinear vehicle parameters are investigated by using NSGA-II. The two objective functions are established based on RMS error between simulation and benchmark system. A stiffer suspension provides good stability and handling during manoeuvres while softer suspension gives better ride quality. The final results indicated that the newly developed nonlinear vehicle model is behaving accurately with input ride and manoeuvre. The outputs trend are successfully replicated.
A Study on how Spot Welds Affect the Stiffness of a Car Body T-jointsaeid ghaffari
* only the first 6 pages of this project is presented here. If you are interested to study the rest of this document please contact me via saeid.ghaffari@studenti.polito.it.
With respect to the importance of the T-joint in a vehicle body strength, this project aims to study the joint torsional and bending stiffness in the two main directions. Furthermore, the influence of the number of spot welds on the stiffness of the joint will be analysed benefiting from Altair Hyperworks (Hypermesh FEA software).
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.
AUTOMOTIVE COMPUTATIONAL FLUID DYNAMICS SIMULATION OF A CAR USING ANSYSIAEME Publication
In this paper, ANSYS CFX method is used to simulate a single car model with and without a spoiler and by using two types of mesh. The solution of the Reynolds average Navier Stokes equations (RANS equations) has been achieved by using two models such as K-Epsilon and K –Omega Turbulence model will be analysed. In this report, mesh quality, boundary layer and turbulent y+ value simulation has been thoroughly analysed and solution for both the models has also been compared and discussed the results. We use the ANSYS software to determine the drag and lift forces at different turbulence kinetic energy variables k-Epsilon and K-Omega for the given vehicle domain. Further, the effects of aerodynamic are verified with and without the spoiler.
Modeling and Analysis of Tractor Trolley Axle Using AnsysIOSR Journals
Abstract: Tractor trolley (or) trailers are very popular and cheaper mode of goods and transport in rural as
well as urban areas. In India, various small scale industries are adopting the crude methodologies for designing
and manufacturing machine components. One such industry producing tractor trolleys for agricultural use has
been identified for this study. In this paper a static analysis is conducted on a tractor trolley axle. The solid
modeling of axle is developed by CATIA-V5. Analysis is done using ANSYS work bench. Most of the tractor
trolley axle used today is rectangular cross section type which in turn leads to increase in the weight of tractor
trolley and axle. In this paper an attempt has made by replacing rectangular cross section with circular section
which result in reducing the weight of the axle and the cost.
Performance Study of Wind Friction Reduction Attachments for Van Using Comput...IJERA Editor
Road transport is the key factor as it is the major method to connect places through land. Along with wide use of internal combustion engines for this purpose comes the massive consumption of fossil fuels by vehicles. Most of the research today is toward making efficient machines. This paper mainly deals with providing attachments to existing models of vehicle to make it more efficient. An assessment of the impact of aerodynamic drag and its relationship to energy consumption presented. A few models are designed and analysed for reducing drag with the help of Attachments. Solid works is used to model and ANSYS Fluent is used for CFD analysis. The results of Cd of various configuration is analysed, 0.427 being the Cd for conventional Van is reduced to 0.234 for van with front and rear attachment.
CFD Simulation for Flow over Passenger Car Using Tail Plates for Aerodynamic ...IOSR Journals
This work proposes an effective numerical model based on the Computational Fluid Dynamics
(CFD) approach to obtain the flow structure around a passenger car with Tail Plates. The experimental work of
the test vehicle and grid system is constructed by ANSYS-14.0. FLUENT which is the CFD solver & employed in
the present work. In this study, numerical iterations are completed, then after aerodynamic data and detailed
complicated flow structure are visualized.
In the present work, model of generic passenger car has been developed in solid works-10 and
generated the wind tunnel and applied the boundary conditions in ANSYS workbench 14.0 platform then after
testing and simulation has been performed for the evaluation of drag coefficient for passenger car. In another
case, the aerodynamics of the most suitable design of tail plate is introduced and analysedfor the evaluation of
drag coefficient for passenger car. The addition of tail plates results in a reduction of the drag-coefficient
3.87% and lift coefficient 16.62% in head-on wind. Rounding the edges partially reduces drag in head-on wind
but does not bring about the significant improvements in the aerodynamic efficiency of the passenger car with
tail plates, it can be obtained. Hence, the drag force can be reduced by using add on devices on vehicle and fuel
economy, stability of a passenger car can be improved.
SIMULTANEOUS OPTIMIZATION OF SEMIACTIVE QUARTER CAR SUSPENSION PARAMETERS USI...ijmech
In present paper, a methodology is presented related to the optimization of semi-active quarter car model
suspension parameters having three degrees of freedom, subjected to bump type of road excitation.
Influence of primary suspension stiffness, primary suspension damping, secondary suspension stiffness and
secondary suspension damping are studied on the passenger ride comfort, taking root mean square (RMS)
values of passenger seat displacement and settling time into account. Semi-active quarter car model
assembled with magneto-rheological (MR) shock absorber is selected for optimization of suspension
parameters using Taguchi method in combination with Grey relational analysis. Confirmatory results with
simulation run indicates that the optimized results of suspension parameters are helpful in achieving the
best ride comfort to travelling passengers in terms of minimization of passenger seat displacement and
settling time values.
Assessment of Flow Control using Passive Devices around Bluff BodiesAnuragSingh1049
This article presents a review study on the experimental investigation of aerodynamic force on a car like bluff bodies along with the simulations using different turbulence models used in CFD (Computational Fluid Dynamics). The aim of the study is to find a useful method for the better design of a car body. It was observed that combination of wind tunnel experiments and CFD computation can lead to better aerodynamic design. Significant reduction in coefficient of the lift and drag for a car model were found when a more streamlined body design was adopted. Appropriate change in the slant angle for the car body can significantly reduce the fuel consumption. Also, the use of simulations in combination with the experimental observations helps in predicting the flow behavior more accurately.
Assessing the Aerodynamic Performance of a Formula SAE Model by means of CFD ...saeid ghaffari
A simplified race car model is used in this project to analyse the aerodynamic performance of a Formula SAE car by means of CFD simulation. First, the simulation workflow in Star-CCM+ will be demonstrated. Then, before applying volumetric controls and prism-layer mesh refinement to obtain more accurate results, tools to judge solution convergence are introduced.
*the first six pages of this project are presented here. If you are interested to study the rest of this document, please contact me via saeid.ghaffari@studenti.polito.it.
Selection of powertrain for vehicle is depends upon vehicle type & application of vehicle. To achieve performance of vehicle, engine torque at maximum revolutions, Transmission ratio, Axle ratio & tire plays important role. In order to understand vehicle performance in theoretical calculation there should be proper selection of power train aggregates. All these aggregates technically will evaluate the actual vehicle performances. For example, trucks are seldom run at their rated maximum speed. In fact, they are usually operated with engine speed at maximum torque or at the speed where fuel consumption is minimized. In climbing hills, there may be occasions when the engine revolution is raised to its maximum to produce the maximum horsepower; however, the most efficient method of operation is to use the range of engine speed, which maximizes torque. If an engine's speed range, producing maximum torque, is extremely narrow, a slight increase of rpm will cause a substantial loss of power and sign of poor performance characteristic. In other words, engines with high maximum torque and horsepower are not necessarily the most "powerful engine." Factors other than the maximum values of the torque and horsepower must be evaluated in determining the practical performance of engines. Furthermore, a high performance engine must be combined with the correct transmission and differential in order to produce the desired running performance. It is necessary to understand the factors affecting its ease of operations. This Paper tells how to integrate powertrain and judge performance of vehicle according to application and type of vehicle by reading performance curves and calculation
Design modification on Indian Road Vehicles to Reduce Aerodynamic DragIJAEMSJORNAL
Reducing vehicle fuel consumption has become one of the most important issues in recent years. Aerodynamic drag contributes to 50-60% of fuel consumption in trucks on highways. Vehicle aerodynamic performance is mainly determined by drag coefficient, which directly affects engine requirements and fuel consumption. It’s well known that drag changes in a crosswind compared with a condition without a crosswind, and that the change depends on the vehicle shape. Pressure drag, a major drag for trucks as they run at lower speeds is produced by the shape of the object. Therefore, addition of some components can suffice the need. The vehicle has been designed by using Catia and then analysed with CFD. The values are compared and the resultant drag reduction is calculated.
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.
Newly Developed Nonlinear Vehicle Model for an Active Anti-roll Bar SystemjournalBEEI
This paper presents the development of a newly developed nonlinear vehicle model is used in the validation process of the vehicle model. The parameters chosen in a newly developed vehicle model is developed based on CARSIM vehicle model by using non-dominated sorting genetic algorithm version II (NSGA-II) optimization method. The ride comfort and handling performances have been one of the main objective to fulfil the expectation of customers in the vehicle development. Full nonlinear vehicle model which consists of ride, handling and Magic tyre subsystems has been derived and developed in MATLAB/Simulink. Then, optimum values of the full nonlinear vehicle parameters are investigated by using NSGA-II. The two objective functions are established based on RMS error between simulation and benchmark system. A stiffer suspension provides good stability and handling during manoeuvres while softer suspension gives better ride quality. The final results indicated that the newly developed nonlinear vehicle model is behaving accurately with input ride and manoeuvre. The outputs trend are successfully replicated.
A Study on how Spot Welds Affect the Stiffness of a Car Body T-jointsaeid ghaffari
* only the first 6 pages of this project is presented here. If you are interested to study the rest of this document please contact me via saeid.ghaffari@studenti.polito.it.
With respect to the importance of the T-joint in a vehicle body strength, this project aims to study the joint torsional and bending stiffness in the two main directions. Furthermore, the influence of the number of spot welds on the stiffness of the joint will be analysed benefiting from Altair Hyperworks (Hypermesh FEA software).
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.
AUTOMOTIVE COMPUTATIONAL FLUID DYNAMICS SIMULATION OF A CAR USING ANSYSIAEME Publication
In this paper, ANSYS CFX method is used to simulate a single car model with and without a spoiler and by using two types of mesh. The solution of the Reynolds average Navier Stokes equations (RANS equations) has been achieved by using two models such as K-Epsilon and K –Omega Turbulence model will be analysed. In this report, mesh quality, boundary layer and turbulent y+ value simulation has been thoroughly analysed and solution for both the models has also been compared and discussed the results. We use the ANSYS software to determine the drag and lift forces at different turbulence kinetic energy variables k-Epsilon and K-Omega for the given vehicle domain. Further, the effects of aerodynamic are verified with and without the spoiler.
Modeling and Analysis of Tractor Trolley Axle Using AnsysIOSR Journals
Abstract: Tractor trolley (or) trailers are very popular and cheaper mode of goods and transport in rural as
well as urban areas. In India, various small scale industries are adopting the crude methodologies for designing
and manufacturing machine components. One such industry producing tractor trolleys for agricultural use has
been identified for this study. In this paper a static analysis is conducted on a tractor trolley axle. The solid
modeling of axle is developed by CATIA-V5. Analysis is done using ANSYS work bench. Most of the tractor
trolley axle used today is rectangular cross section type which in turn leads to increase in the weight of tractor
trolley and axle. In this paper an attempt has made by replacing rectangular cross section with circular section
which result in reducing the weight of the axle and the cost.
Investigations of Drag and Lift Forces Over the Profiles of Car Using CFDijsrd.com
Aerodynamic characteristics of racing car are of significant interest in reducing racing accidents due to wind loading and save the fuel consumption. This work outlines the process taken to optimize the geometry of a vehicle. Vertices and edges of car were imported into GAMBIT and a computational domain is created. An unstructured triangular mesh was then applied. The goal is to obtain a better flow around the car model to lower the coefficient of drag force; the work is carried out in a ANSYS CFD FLUENT program towards a converged solution. These practices are helpful to redesign existing vehicles in order to improve handling and increase fuel efficiency. In the present work an attempt has been made by considering three models of car by varying speed of vehicle, the pressure coefficients and drag coefficients are obtained.
Performance Study of Wind Friction Reduction Attachments for Van Using Comput...IJERA Editor
Road transport is the key factor as it is the major method to connect places through land. Along with wide use of internal combustion engines for this purpose comes the massive consumption of fossil fuels by vehicles. Most of the research today is toward making efficient machines. This paper mainly deals with providing attachments to existing models of vehicle to make it more efficient. An assessment of the impact of aerodynamic drag and its relationship to energy consumption presented. A few models are designed and analysed for reducing drag with the help of Attachments. Solid works is used to model and ANSYS Fluent is used for CFD analysis. The results of Cd of various configuration is analysed, 0.427 being the Cd for conventional Van is reduced to 0.234 for van with front and rear attachment
Automotive aerodynamics is the study of the aerodynamics of road vehicles. Its main goals are reducing drag and wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds. Air is also considered a fluid in this case.
Wind-induced Stress Analysis of Front Bumpertheijes
At high velocities, such as on highways, the relative velocity between the oncoming wind and side winds is very high. The high velocity winds that act on the bumper induce certain stresses on it. These stresses may cause deformation of the bumper; if this deformation exceeds a predesigned value, the functionality of the bumper may be hampered. This may result in safety issues and other design issues. In this paper, the effect and nature of these stresses have been quantified by conducting a wind-induced stress analysis on a model of the bumper. The bumper selected is that of Jeep Wrangler and the modelling is done on Creo 2.2. The CFD simulation and structural analysis is conducted on Ansys Workbench 15. The structural analysis and fluid flow data is summarized alongwith the deformation and induced stress values.
Computational Aerodynamics Research and Vehicle Engineering Development (CAR-...inventionjournals
Many Persons, both from industry and also private individuals have performed research in regards to this new issue. Many have performed research on aerodynamics on certain portions of the vehicle and also on effects of shape of the body and other technologies used such as Computational Fluid Dynamics and Wind tunnel Testing.The effects of these studies is seen in the industry today. Not so long ago,the vehicles were having shapes lose to boxes and today beautiful curves dominate the vehicles bodies. These curves not only help in the beauty of the vehicle but also help the vehicle in terms of aerodynamics and fuel efficiency. In this paper we would like to highlight some important topics related with aerodynamics and how they affect the drag of the vehicles. We shall also discuss on methods used in the industry today to calculate the aerodynamic efficiency of the vehicles and their effects.
Car’s Aerodynamic Characteristics at High Speed Influenced by Rear SpoilerIJRES Journal
The factors affect the rear spoiler’s aerodynamics characteristics are cross-sectional shape, chord length and angle of attack. By changing the three factors that can change the state of the car flow field. Determine the main body size, build models by Solidworks . Use Hypermesh to mesh, increase the number of grid near the body especially at the rear spoiler. Use Fluent for fluid analysis to get the values of aerodynamic lift coefficient CL (at 120km / h) based on orthogonal experiments. After calculating, obtain significance order of factors can obtain the best rear spoiler shape, helping to optimize the automotive styling quickly, improve the car's power and economy, ease the new car quickly seize the market.
Design of Rear wing for high performance cars and Simulation using Computatio...IJTET Journal
The performance of a sports car is not only limited to its engine power but also to aerodynamic properties of the car. By decreasing the drag force it is possible to reduce the engine power required to achieve same top speed thus decreasing the fuel requirement. The stability of a sports car is considerably important at high speed. The provision of a rear wing increases the downforce thus reducing the rear axle lift and provides increased traction. In this study an optimum rear wing is designed for the high performance car so as to decrease drag and increase downforce. The CAD designed baseline model with or without rear wing is being analyzed in computational fluid dynamics software. The lift and drag coefficient are calculated for all the design thus an optimum rear wing is designed for the considered baseline model.
Aerodynamic analysis and optimization of wind deflector in a Commercial load ...AM Publications
In the field of commercial goods transport, trucks have an important place. One of the main problems faced by truck manufacturers is the Air resistance associated with the highway running. Since trucks have a large frontal area and the presence of a trailer also leads to the truck experiencing significant resistance which has to be overcome. This can be reduced through the use of wind deflectors. A well-designed wind deflector can reduce wind resistance to a certain extent. Optimizing the angle of the wind deflector also causes reduced drag force acting on the vehicle, thereby reducing the fuel intake. Here the initial drag of 2050 N is reduced to 1688.453 N using a 1.75 m wind deflector at 45 degree angle resulting in the reduction of drag by 17.6%.
1. Department of Aeronautical and Automobile Engineering MIT, Manipal
External Aerodynamic analysis of HCVs
using simulation & wind tunnel techniques
By
Amit Jain (080934122)
Under the guidance of
Mr. Laxmikant G. Keni
Assistant Professor
Dept.of Aeronautical &
Automobile Engineering
MIT, Manipal
2. CONTENTS
• Introduction
• Literature review
• Summary
• Problem definition
• Objective
• Methodology
• future work
• References
Department of Aeronautical and Automobile Engineering MIT, Manipal
3. Department of Aeronautical and Automobile Engineering MIT, Manipal
INTRODUCTION
• The rapidly increasing fuel prices and the regulation of green
house gases to control global warming have given tremendous
pressure on the design engineers to enhance the current
designs of automobile using minimal changes in the shapes.
• To fulfill the above requirements, design engineers have been
using the concepts of aerodynamics to enhance the efficiency of
automobiles.
• Aerodynamics is used by design engineers for cooling engines,
improving the performance of the vehicle, enhancing the comfort
of the rider, stabilizing the car in external wind conditions and
also increasing the visibility of the rider.
4. Department of Aeronautical and Automobile Engineering MIT, Manipal
Spectrum of task for vehicle
aerodynamics
5. Department of Aeronautical and Automobile Engineering MIT, Manipal
PERFORMANCE FACTOR
Fuel consumption is a function of power required at the wheels and
overall engine-accessories-driveline efficiency.
Factors that affect fuel consumption at steady speeds over level
terrain are:
(a) Power Output-Engine-Accessory- Driveline System:
• Basic engine characteristics; fuel consumption vs. RPM and
BHP.
• Overall transmission and drive axle gear ratios.
• Power train loss; frictional losses in overall gear reduction
system.
• Power losses due to fan, alternator, air-conditioning, power
steering, and any other engine-driven accessories.
6. Department of Aeronautical and Automobile Engineering MIT, Manipal
(b) Power Required - Vehicle and Tires
The horsepower required for a vehicle to sustain a given
speed is a function of the vehicle’s total drag. The greater
the drag, the more horsepower is required. The total
vehicle drag can be broken into two main components;
aerodynamic drag and tire drag. Factors affecting these
components are:
• Aerodynamic – Vehicle speed
• Vehicle Frontal area
• Vehicle Shape
• Tire – Vehicle Gross Weight
• Tire Rolling Resistance
7. Department of Aeronautical and Automobile Engineering MIT, Manipal
Both aerodynamic drag and tire drag are influenced by vehicle speed. It is
important, though, to note that speed has a much greater affect on
aerodynamic drag than on tire drag. Figure 1.
8. Department of Aeronautical and Automobile Engineering MIT, Manipal
Gains in fuel economy can be made by either optimizing or reducing some
of the factors affecting drag.
The shape of the vehicle uses about 3 % of fuel to overcome the resistance in
urban driving, while it takes 11% of fuel for the highway driving. This
considerable high value of fuel usage in highway driving attracts several
design engineers to enhance the aerodynamics of the vehicle using minimal
design changes.
9. Department of Aeronautical and Automobile Engineering MIT, Manipal
LITERATURE REVIEW
Dr. Ilhan Bayraktar, Old Dominion University :
His project focuses on analyzing ground vehicle aerodynamics and understanding
complex wake flow behind vehicle bodies.
His study shows that most of the drag force takes place due to the
separation of the flow at the back of the vehicle.
His Computational studies show that about 80% of total drag is from pressure
drag, and the rest is from friction. The maximum pressure difference is observed
at the back surface of the truck, where complex flow phenomena, such as
separation, reattachment and vortices are found.
10. Department of Aeronautical and Automobile Engineering MIT, Manipal
Jaswanth Chowdary U, Tata Consultancy Services Pvt. Ltd. :
Vortex-Generators used over the Audi R8 car model, for drag reduction. For the
research work, a 1:18 model was taken and analyzed in a wind tunnel.
Vortex Generators (VG) placed directly above B-Pillar of the test model whose
frontal area is 8.25X10-3 m² and with dimensions 262*90*75 mm3.
The Drag is reduced with the VG placed at 45 degrees and 90 degrees
considerably due to the increase in the flow velocity at the trailing edge which led
to the delay in the flow separation. The separation caused by the VG induces a
turbulence in the flow thereby reducing the vortex formation.
Results show that drag is reduced but the variation not being gradual may pose
problems with drive handling. The instabilities may increase Lift force or vortices in
the flow and the Yaw moment on the car which is undesirable. Thus the optimum
inclination (it varies from model to model) for the present model is 45 degrees as
relatively low drag is enacted .
11. Department of Aeronautical and Automobile Engineering MIT, Manipal
Xu Wei-gang, Wen Gui-jin, China National Heavy Duty Truck Group Co. Ltd :
Computational Fluid Dynamics (CFD) simulation for two types of heavy commercial
vehicle (one with aerodynamic drag reduction devices and the other without) is
performed to investigate their aerodynamic characteristics.
Through the analysis of airflow and pressure distribution on the full vehicle surface,
the drag reduction mechanism and the influence of these drag reduction devices
on commercial vehicle’s aerodynamic characteristics are discussed.
Result shows that by adding aerodynamic drag reduction devices such as wind
deflector and dome, the aerodynamic drag coefficient of heavy commercial vehicle
significantly reduces 10%.
12. Department of Aeronautical and Automobile Engineering MIT, Manipal
SUMMARY
From the literature survey it is observed that:
• About 80% of total drag is from pressure drag, and the rest is from friction.
• Drag can be reduced by placing the vortex generators over the vehicle
surface, which can further help increasing the speed of the vehicle. But this
technology is in nascent stage in automotive field.
• There is a increase in fuel efficiency, by simply changing the shape of the
vehicle. Actually by using the add on such as Wind deflector, modifications at
the back of the trailer, etc.
13. Department of Aeronautical and Automobile Engineering MIT, Manipal
PROBLEM DEFINITION
External Aerodynamic flow analysis of
HCVs using simulation & wind tunnel
techniques & implementation of
various techniques to reduce drag,
improve fuel efficiency and vehicle
performance.
14. Department of Aeronautical and Automobile Engineering MIT, Manipal
OBJECTIVE
The main objective of this project was to study the
coefficient of drag of Heavy commercial vehicle
while using the different shape and height of wind
deflectors.
15. Department of Aeronautical and Automobile Engineering MIT, Manipal
METHODOLOGY
The main steps involved are:
1. Generation of 3D solid models by using CATIA V5 R19.
2. analysis of the flow and drag force patterns of the models by using ANSYS-
CFX software.
3. Comparison of results obtain.
4. Validation of simulation results will be done by sub sonic wind tunnel
testing.
16. Department of Aeronautical and Automobile Engineering MIT, Manipal
1. Generation of 3D solid models by using CATIA V5 R19.
• Blue print is obtained from the website.
• Rough dimensions are taken such as height, width, wheel base and length of
the vehicle.
• Left side view of the model is generated by using drafting software (CATIA V5
R19).
• Coordinates are obtained from this left side view in order to obtain fine
geometry.
• From these coordinates 3d models are generated, by giving fine dimensions in
the product design module of CATIA V5 R19.
17. Department of Aeronautical and Automobile Engineering MIT, Manipal
1. Normal model dimensions which resembles to EICHER truck
23. 3. 3D model with triangular shaped wind deflector
24. Generation of the meshed model
The IGS file of the model is imported into ANSYS Workbench. Here the body
of (vehicle) was subtracted from the body of the channel to leave the region of
interest for CFD simulation. The CFD simulation involves meshing, setting the
initial conditions, solution and post processing the result.
4. Vehicle geometry after import, in ANSYS CFX
• Geometry Creation
25. 5. Generation of box (channel) around the vehicle body
In this project, the length of the computational field is approximately fourteen
times of the vehicle lengths. The inlet is 4 times of the vehicle lengths far
from ahead of the vehicle and outlet is 9 times of the vehicle lengths far from
the container’s back. The height and the width of the computational field are
5 times of the vehicle heights and 7 times of the vehicle widths respectively.
Ground clearance is 30 mm.
27. • Meshing
Six regions are defined in the model, one each for the four walls of the channel, inlet, and outlet. A
separate region is created for the body, for visualization purposes and setting mesh controls. To create a
fine mesh around the surface of the body, face spacing was created to concentrate nodes and elements
in this region. To create a layer of thin prismatic elements around the body surface inflation was used.
The values of parameters of facing spacing and inflation are:
28. 7. Selection of inflated boundary
To create a layer of thin prismatic elements around the body surface
inflation was used.
29. After values of the above parameter are set as mentioned in the figure the surface
mesh and then the volume mesh was generated.
Surface mesh of the body Surface mesh of side of the channel
31. • Setting the boundary and initial conditions for flow simulation
The flow simulation and analysis for the model was done using general purpose fluid
dynamics program, ANSYS CFX V12.0. A flow domain is defined for running the simulation in
ANSYS CFX Pre. The flow in the domain is expected to be turbulent and the Shear Stress
Transport Turbulence model is used with automatic wall function treatment because of its
highly accurate assessment of flow separation. Here we are modeling a compressible flow to
calculate density variation thus a realistic value of reference pressure must be specified
because many properties of the fluid are calculated on the basis of absolute pressure (static
pressure plus reference pressure).
Table 1 Parameters of the fluid domain
Air at 25o
C
Morphology Continuous Fluid
Buoyancy Model Non Buoyant
Domain Motion Stationary
Heat Transfer Isothermal
Fluid Temperature 298 K
Turbulence Model Shear Stress Transport
32. Table 2 Boundary conditions for the inlet and outlet
BOUNDARY TYPE (INLET)
Flow regime Subsonic
Normal speed 15ms-1
(for all models)
Turbulence Option Medium Intensity and Eddy Viscosity Ratio
Mass And Momentum Normal Speed
BOUNDARY TYPE (OUTLET)
Flow Regime Subsonic
Mass and Momentum Option Static Pressure
Relative Pressure 0 Pascal
Channel after defining the computational field
33. Table 3 Solver control parameters
Maximum Iterations 100
Fluid Time Scale Physical Timescale
Physical Timescale 0.2 seconds (for speed of 15ms-1
)
Convergence Criteria (residual Target) 1e-05
The boundary conditions for the top and side walls of the channels is set as “free slip” and “adiabatic wall”
but that for the bottom wall is set as “no slip” and “adiabatic wall” as it simulates the ground effect. The
boundary condition for the body in the channel is also set as “wall” and “no slip”. Then the initial values of
the X, Y and Z components of fluid velocity are specified. In this model the values of X and Z components
are 0 as the direction of the fluid flow is along positive Y axis. Then the solver control is defined.
Physical timescale provides sufficient relaxation for the equation non-linarites so that a converged
steady state solution is obtained. It can be approximated as the Dynamic Time of the flow. It is
nothing but the time taken by a point in the flow to pass through the fluid domain.
34. The above procedure for analysis is followed in all the models with different configurations.
Table 4 Curve shaped wind deflector height data
Curve shaped wind deflector height (from the ground) Frontal area
(96,140), (15,160), (50,155) 160 mm 0.02 m2
(96,140), (15,165), (50,160) 165 mm 0.02 m2
(96,140), (15,170), (50,165) 170 mm 0.02 m2
(96,140), (15,175), (50,170) 175 mm 0.020331m2
(96,140), (15,180), (50,175) 180 mm 0.021006m2
Figure 3.15 Creation of CAD model of truck with curve shaped wind deflector (96,140),
(15,180), (50,175) 180 mm (Height)
35. Table 5 Triangular shaped wind deflector height data
Triangular shaped wind deflector height (from the ground) Frontal area
(96,140), (15,160) 160 mm 0.02 m2
(96,140), (15,165) 165 mm 0.02 m2
(96,140), (15,170) 170 mm 0.02 m2
(96,140), (15,175) 175 mm 0.020331m2
(96,140), (15,180) 180 mm 0.021006m2
Figure 3.16 Creation of CAD model of truck with curve shaped wind deflector (96,140),
(15,180) 180 mm (height
36. 160 mm 160 mm
165 mm 165 mm
170 mm 170 mm
175 mm 175 mm
200 mm 200 mm
Figure 3.17 Different configurations of truck with curve & triangular shaped wind deflector
(with varying height)
37. All the above models were tested with the same procedure in ANSYS CFX at 15 m/s and
results were obtained.
Equations used:
38. • Wind tunnel testing
In this methodology we will discuss
1. The modelling of scaled HCV models.
i. HCV without wind deflector
ii. HCV truck with curve wind deflector
iii. HCV truck with triangular wind deflector
2. Calibration of sub sonic wind tunnel.
3. Smoke flow visualisation technique for all the three models.
4. Surface pressure distribution over a bluff body (HCV models)
41. • Modeling of scaled model
1. Modeling
The modelling of the three HCV models was done in CATIA V5 R19 in scaled dimension of
1:20 which was used as a blue print for the preparation of the models to be used in
experimental analysis.
2. Construction of models
MATERIALS USED
1. Plaster of paris
2. Aluminium sheet
3. Engineering drawing board
4. Sand paper
5. Aluminium foil
6. Black tape
7. Duct tape
8. Pressure tubes (dia 0.6mm )
9. Connecting tubes (dia 0.8mm)
10. pins
• Tools used
The following tools were used during the preparation of the
scaled HCV models
1. Bosch drilling machine
2. 4 mm drill bit
3. Hammer
4. Metal sheet cutter
5. Pliers
6. Scissors
7. Mallet
42. Fig.3.20 Outline sketch of model drawn on aluminium foil
• Preparation of the models
Preparation of the models
1. An engineering drawing board was taken and aluminium foil was wrapped over it to
facilitate the drawing of the scaled outline of the HCV model which was to be
prepared.
2. The outline sketch was drawn on the aluminium foil using marker pen .all the
important coordinates were marked using pins and joined by lines to get the outline.
43. Fig 3.21. Aluminium sheet in desired curved shape with members joined by black tape.
3. The aluminium sheet was then cut according to the dimensions of the model using a
metal sheet cutter. The height, width and length were all take into consideration while
cutting the sheet.
4. The metal sheet was placed in such a way that the side of the scaled model would be
the base of the model.
5. Parts of the metal sheet were joined using black tape/duct tape.
6. The frontal parts like the wind shield, front grille, bumper, wind deflector which were
to be given curved shape were created using a mallet which was used to get the
desired shape from the aluminium sheet.
44. Fig 3.22 The slurry solidifying inside the mould of desired shape
7. The central line of the sheet was marked starting from the front bumper to the wind
deflector’s topmost part.
8. Points were marked at equal distances and on important points where pressure
difference was to be measured.
45. 9. A Bosch drilling machine with 4mm drill bit was then used to drill holes at these points through which the receiving part
of the pressure tube was to be placed.
10. A hole was made at the base of the model from where the rear end of all the ten pressure tubes would come out. This
end would be connected to the manometer for taking the readings.
11. The curved shaped sheet was then placed on the marked coordinates and wound around pins which were used to
denote important coordinates.
12. This sheet was then placed firmly on the aluminum foil by the help of black tape which was wound all around the
circumference of the base and this was done to make the mould leak proof and stable so as to hold the plaster of paris
mixture.
13. The pressure tubes were then placed in their respective positions and were numbered from 1 to 10.
14. Plaster of paris was then taken and mixed with water to form a slurry of ideal properties which would set into solid in
around six hours.
15. The slurry was stirred constantly to keep the mixture uniform and not form unwanted mounds.
16. Carefully the slurry was poured into the aluminum sheet mould and the mould was filled by plaster of paris till the
marked height.
17. The exposed region of the mould was given finishing using sand paper and smooth surface finish was given using
lime.
18. The slurry was left to solidify for around 6 hours without any disturbance.
19. The slurry solidified and took the shape of the mould desirably.
46. FINISHED SCALED MODELS
1. HCV without wind deflector
Fig 3.23 Front view (pressure ports visible at the front)
50. Calibration of subsonic wind tunnel:
A calibration chart was prepared which gave us the mean speed at the working
section in terms of the reading of the upstream pressure tapping.
EQUIPMENTS USED
1. Sub sonic wind tunnel
2. Multi tube manometer
3. Pitot static tube
Fig.3.32 Multi tube manometer
53. RESULT ANALYSIS
This section includes the aerodynamic (numerically as well as
experimentally) analysis that was done on HCV under three different design
configurations but under same environmental conditions. In all the above
mentioned cases, air velocity of 15m/s at the inlet and relative pressure
zero at the outlet is applied. Three different models of HCV’s are used
throughout the analysis i.e. Basic HCV model, HCV model with curve
shaped wind deflector and HCV model with triangular shaped wind
deflector. After validating, the numerical analyses of these models with
experimental analysis, we further study the effect of shape and height of the
wind deflectors. The results in all the cases are compiled in the form of
screenshots of the ANSYS CFX window.
i. Numerical analysis
ii. Experimental analysis
54. i. Numerical analysis
1. Screenshots for, air velocity =15m/s (Model 1)
Fig 4.1 Streamline flow over the HCV base model
55. 2. Screenshots for the HCV with curve shaped wind deflector model case, air velocity 15m/s.
Fig 4.2 streamline flow around HCV with curve shaped wind deflector (Model 2)
56. 3. Screenshots for the HCV with triangular shaped wind deflector model case, air velocity
15m/s.
Fig 4.3. streamline flow around HCV with triangular shaped wind deflector (Model 3)
57. Airflow distribution analysis
Airflow field around the model and flow separation as well as tail vortex on
the model can be observed by airflow distribution. Different front airflow
separations lead to different tail vortex in the rear of the container.
According to W. Hucho, the elimination of the tail vortex can reduced the
drag. The smaller the trail vortex is, the smaller the vehicle's aerodynamic
drag. As model 2 & 3 have a smaller vortex, so they have smaller
aerodynamic drag coefficient than that of model 1.
60. Fig 4.6 Pressure contour around the HCV with triangular shaped wind deflector
61. Fig 4.7 Pressure over the HCV with curve shaped wind deflector (height = 170mm)
62. Fig 4.8 Pressure over the HCV with curve shaped wind deflector (height = 170mm)
63. Pressure distribution analysis
The distribution of pressure around the vehicle is mainly affected by air
velocity around the vehicle. Vortex generated by airflow separation evidently
changes the distribution of pressure. Giving a definite external shape, the
reduction of vertex generated by airflow separation is the major way to
reduce the aerodynamic drag. The above figures show that both on model 1,
model 2 and model 3, pressure on front grill and the bottom of windshield
glass is high, while on the front top of the cab is low. On front of the
container, there is an especially high pressure area on model 1.
65. Fig 4.10 velocity contours around HCV with curve shaped wind deflector (height =170mm)
66. Fig 4.11 Velocity contours around the HCV with triangular shaped wind deflector.
From above figures, we can see that model 1 has the
highest vortex generation at back of its container which is
the main cause of high coefficient of drag. Cd =0.6971
67. 1. HCV base model case (Model 1)
force_y()@body = 1.91361 [N] (drag force) Cd = 0.6971
force_z()@body = -0.334936 [N] (lift force)
force_x()@body = -0.0101962 [N] (side force)
2. HCV with curve shaped wind deflector case (Model 2)
force_y()@body = 1.6998 [N]
force_z()@body = -0.511125 [N] Cd = 0.6192
force_x()@body = 0.0170118 [N]
3. HCV with triangular shaped wind deflector model case (Model 3)
force_y()@body = 1.67544 [N]
force_z()@body = -0.465912 [N] Cd = 0.6103
force_x()@body = -0.0213523 [N]
Simulation Results
68. ii. Experimental analysis
In this analysis we will
1. Calibrate the sub sonic wind tunnel with necessary tabulation and calculation
2. Analyse the smoke flow visualisation of the three bluff bodies.
3. Calculate the surface pressure distribution over the bluff bodies and calculate
their coefficient of drag.
70. SAMPLE CALCULATIONS-
Reading no. 1, rpm= 60,
Initial reading=16 mm
Final reading =17 mm
Difference in reading H= 17-16=1mm
Therefore V=3.62
V=3.62
V=2.55 m/sec
Using the above formula for our experimental use we require 15 m/sec which comes out to be
520 rpm
Fig.4.12 Wind tunnel running at 520 rpm or 15 m/sec
71. • Analysis of smoke flow visualizations of bluff bodies
FIG 4.13 Streamlined flow over the body
We observed streamlined flow over the body which was at a distance from the body and there
was visible low pressure over the cabin which increased the drag and hence by the use of
wind deflector this effect has to be reduced.
72. Fig.4.14 Streamlined flow over HCV with curved wind deflector
We observed streamlined flow over the body which was at a distance from the body and
because of the wind deflector there was no low pressure region and the flow was streamlined
throughout hence reducing drag and giving favourable outcome.
73. Fig.4.15 Streamlined flow over hcv with triangular wind deflector
Here also we observed streamlined flow over the body which was at a distance from the body
and because of the wind deflector there was no low pressure region and the flow was
streamlined throughout hence reducing drag and giving favourable outcome
74. • Calculating the surface pressure distribution over the bluff bodies and calculating
their coefficient of drag.
The drag coefficient (commonly denoted as: cd, cx or cw) is a dimensionless quantity that is
used to quantify the drag or resistance of an object in a fluid environment such as air or
water. It is used in the drag equation-
Where:
Is the drag force, which is by definition the force component in the direction of
the flow velocity
Is the mass density of the fluid which is air (1.1 kg/m3)
Is the speed of the object relative to the fluid (which is 15 m/s for our analysis)
Is the reference area
Here =P.A
Where P=static pressure
& A is the projected area
75. Since our bluff body has a frontal area in the shape of a rectangle the projected and reference
area both are same and cancel out in the numerator and denominator.
P the static pressure is the mean of the static pressures at all the ten station ports.
From the change in height of the working fluid in the manometer we can calculate the static
pressure change using the following formula
Where
-density of working fluid i.e ethyl alcohol which is 800 kg/m3
h- Change in height of working fluid
A compressible fluid at rest is governed by the statics equation,
Where z is the height above an arbitrary datum, and g is the gravity acceleration constant
(9.81 m/s2
). This equation describes the pressure profile of the atmosphere, for example.
For an incompressible fluid, the statics equation simplifies to,
76. HCV WITHOUT WIND DEFLECTOR-CALCULATING ITS SURFACE PRESSURE
DISTRIBUTION AND COEFFICIENT OF DRAG
Table 7 Pressure at various pressure points
Serial no. Port no.
Initial height
h1(mm)
Final height
h2 (mm)
Difference in
height
h2- h1(mm)
P
Static
pressure(in
Pa)
1 1 30 39 9 70.63
2 2 30 42 14 109.87
3 3 30 51 21 164.8
4 4 30 49 19 149.11
5 5 30 52 22 172.65
6 6 30 47 18 141.26
7 7 30 40 14 109.87
8 8 30 35 5 39.24
9 9 30 24 -6 -47.08
10 10 30 26 -4 -31.39
77. Now the mean static pressure is calculated by taking the sum of P1-10 and dividing it by the
total number of observations i.e. 10.
Therefore mean pressure comes out to be
(70.63+109.87+164.8+149.11+172.65141.26+109.87+39.24-47.08-31.39)/10=87.59 Pa
Now using the formula
Here =1.1 kg/m3
V=15 m/s
Therefore Cd=87.59×2/(15)2
×1.1
Hence Cd=0.7078
78. HCV WITH CURVED WIND DEFLECTOR-CALCULATING ITS SURFACE
PRESSURE DISTRIBUTION AND COEFFICIENT OF DRAG
Table 8 Pressure at various pressure points
Serial no. Port no.
Initial height
h1(mm)
Final height
h2 (mm)
Difference in
height
h2- h1(mm)
P
Static
pressure(in
Pa)
1 1 30 39 9 70.63
2 2 30 42 12 94.17
3 3 30 52 22 172.23
4 4 30 51 21 164.80
5 5 30 51 21 164.80
6 6 30 48 18 141.26
7 7 30 39 9 70.63
8 8 30 26 -4 -31.39
9 9 30 25 -5 -39.24
10 10 30 24 -6 -47.08
79. Now the mean static pressure is calculated by taking the sum of P1-10 and dividing it by the
total number of observations i.e 10.
Therefore mean pressure comes out to be =78.88 Pa
Now using the formula
Here =1.1 kg/m3
V=15 m/s
Therefore Cd=78.88×2/(15)2
×1.1
Hence Cd=0.6213
80. HCV WITH TRIANGULAR WIND DEFLECTOR-CALCULATING ITS SURFACE
PRESSURE DISTRIBUTION AND COEFFICIENT OF DRAG
Table 9 pressure at various pressure points
Serial no. Port no.
Initial height
h1(mm)
Final height
h2 (mm)
Difference in
height
h2- h1(mm)
P
Static
pressure(in
Pa)
1 1 30 39 9 70.63
2 2 30 42 12 94.17
3 3 30 52 22 172.56
4 4 30 50 20 156.96
5 5 30 52 22 172.56
6 6 30 49 19 149.11
7 7 30 39 9 70.63
8 8 30 25 -5 -39.24
9 9 30 25 -5 -39.24
10 10 30 24 -6 -47.08
81. Now the mean static pressure is calculated by taking the sum of P1-10 and dividing it by the
total number of observations i.e. 10.
Therefore mean pressure comes out to be =76.11 Pa
Now using the formula
Here =1.1 kg/m3
V=15 m/s
Therefore Cd=76.11×2/(15)2
×1.1
Hence Cd=0.6145
82. Validation and comparison
Table 10 Comparison table
Model Numerical Experimental Difference
1. Base model Cd= 0.69713 Cd= 0.7078 0.01067
2.With Curve shaped wind deflector Cd= 0.61923 Cd= 0.6213 2.07e-3
3.With triangular shaped wind deflector Cd= 0.6103 Cd= 0.6145 4.2e-3
Wind tunnel test and CFD results are compared to demonstrate the correlation of the
two methods. The scale of the wind tunnel test model is 1:20. Test was performed at
Low speed wind tunnel. Table shows the comparison between simulation result and
test result. We can see that the simulation result has better correlation with that of the
test.
The streamline flows over the vehicle body during wind tunnel testing are similar to
that in simulations.
83. After validating above three models, we modified the base model into ten different models
depending upon the height and shape of the wind deflector and tested in ANSYS CFX. Data and
results have been given below.
Table 11 Data table
Curve shaped wind deflector height (from the ground) Frontal area & Cd value
(96,140), (15,160), (50,155) 160 mm 0.02 m2 Cd= 0.66732
(96,140), (15,165), (50,160) 165 mm 0.02 m2 Cd= 0.604539
(96,140), (15,170), (50,165) 170 mm 0.02 m2 Cd= 0.619234
(96,140), (15,175), (50,170) 175 mm 0.020331m2 Cd= 0.65437
(96,140), (15,180), (50,175) 180 mm 0.021006m2 Cd= 0.64469
Triangular shaped wind deflector height
(from the ground)
Frontal area & Cd value
(96,140), (15,160) 160 mm 0.02 m2 Cd= 0.64566
(96,140), (15,165) 165 mm 0.02 m2 Cd= 0.6173
(96,140), (15,170) 170 mm 0.02 m2 Cd= 0.6103
(96,140), (15,175) 175 mm 0.020331m2 Cd= 0.77549
(96,140), (15,180) 180 mm 0.021006m2 Cd= 0.650441
84.
85. In the above result, we can see that lowest coefficient of drag lies in between 165
to 170 mm height (which is less than the height of the container i.e. 170 mm). It
also shows that curve shaped wind deflector is more effective than that of
triangular shaped. Vortex generation in this range of height was very less
compare to others. Hence, less drag will act over the vehicle.
86. Conclusions
By performing a series of CFD simulations, we have investigated the drag
reduction mechanism of commercial vehicle. By adding aerodynamic drag
reduction devices such as wind deflector and dome, the aerodynamic drag
coefficient of heavy commercial vehicle significantly reduces 10%. The
comparison of CFD result with wind tunnel test result reveals the same
trends of the aerodynamic characteristics.
Airflow analysis demonstrates that the wind deflector can reduce drag
successfully and the dome should be improved to match well with the
container. So there is still space to improve the aerodynamic characteristics
of heavy commercial vehicles by further optimization or increase the
aerodynamic drag reduction devices
From the above results we conclude that shape and height of the wind
deflector have great effect on fuel economy of the vehicle. By optimising the
size and shape of the wind deflector, we can increase the fuel efficiency of
the HCV’s. As well as we can cut down the cost of production of wind
deflectors by finding the minimum Cd at the lowest possible height.
87. Significance of the results obtained
• No significant previous projects have worked on the shape and size of the
wind deflectors.
• The speed taken, during the whole analysis was by considering the Indian
road conditions i.e. 15 m/s.
• Pressure distribution obtained was in the similar range when compared to
actual models.
• Streamline flow over the vehicle bodies were mostly the same as in ANSYS
CFX.
88. Future scope of work
• This project took into consideration the height and shape of the wind
deflector for analysis purposes hence leaving room for future study on
the effect of wind deflectors with different angular positions.
• Future research on drag reduction techniques can also take into the
implementation of air ducts at the leading edge & vortex generators at
the trailing edge.
• There is also scope of getting further insight caused by after body
modifications and trying them at different angles & shape.
• Further we can use FLUENT, GAMBIT, HYPERMESH etc. various other
software can be used for analysis. For modeling purpose PRO-E,
UNIGRAPHICS, SOLIDWORKS can be used.
• Future work can also be done on models which have been made by the
process of Rapid prototyping and 3 D printing.
89. REFERENCES
Journal / Conference Papers
[1] Rose McCallen Fred Browand Anthony Leonard,“Progress in Reducing
Aerodynamic Drag for Higher Efficiency of Heavy Duty Trucks Class 7-8 ” ,
SAE TECHNICAL PAPER SERIES: 1999-01-2238
[2] Jason M Ortega Kambiz Salari, “An Experimental Study of Drag Reduction
Devices for a Trailer Underbody and Base”, AIAA-2004-2252 V5
[3] Bonnet C. Fritz H., “External Truck Aerodynamics”
DominionUniversity,Norfolk,VA,USA,2009-03-4104
Reference / Hand Books
[1] Aerodynamics of road vehicles, Wolf-heinrich, SAE International , ISBN- 0-
7680-0029-7
[2] ANSYS CFX reference manual.
Web
[1] NASA Dryden research; www.nasa.gov
[2]SAE International www.sae.org
[3] Lawrence Livermore national laboratory; www.llnm.org
[4]Norfolk state university; www.norfolk.edu