scholarly journals Aerodynamic Shape Optimization Method of Non-Smooth Surfaces for Aerodynamic Drag Reduction on a Minivan

Fluids ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 365
Author(s):  
Zhendong Yang ◽  
Yifeng Jin ◽  
Zhengqi Gu
Keyword(s):  
Drag Reduction ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Flow Characteristics ◽  
Kriging Model ◽  
Optimization Method ◽  
Smooth Surfaces ◽  
Friction Resistance ◽  
Aerodynamic Drag Coefficient

To reduce aerodynamic drag of a minivan, non-smooth surfaces are applied to the minivan’s roof panel design. A steady computational fluid dynamics (CFD) method is used to investigate the aerodynamic drag characteristics. The accuracy of the numerical method is validated by wind tunnel test. The drag reduction effects of rectangle, rhombus and arithmetic progression arrangement for circular concaves are investigated numerically, and then the aerodynamic drag coefficient of the rectangle arrangement with a better drag reduction effect is chosen as the optimization objective. Three parameters, that is, the diameter D of the circular concave, the width W and the longitudinal distance L among the circular concaves, are selected as design variables. A 20-level design of an experimental study using a Latin Hypercube scheme is conducted. The responses of 20 groups of sample points are obtained by CFD simulation, based on which a Kriging model is chosen to create the surrogate-model. The multi-island genetic algorithm is employed to find the optimum solution. The result shows that maximum drag reduction effects up to 7.71% can be achieved with a rectangle circular concaves arrangement. The reduction mechanism of the roof with the circular concaves was discussed. The circular concaves decrease friction resistance of the roof and change the flow characteristics of the recirculation area in the wake of the minivan. The roof with the circular concaves reduces the differential pressure drag of the front and rear of the minivan.

Reduction in the aerodynamic drag around a generic vehicle by using a non-smooth surface

2016 ◽  
Vol 231 (1) ◽  
pp. 130-144 ◽  
Author(s):  
Yiping Wang ◽  
Cheng Wu ◽  
Gangfeng Tan ◽  
Yadong Deng
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Surrogate Model ◽  
Smooth Surface ◽  
Aerodynamic Drag ◽  
Optimal Solution ◽  
Optimization Method ◽  
Aerodynamic Optimization ◽  
Design Variables ◽  
Aerodynamic Drag Coefficient

Numerical investigations are carried out to investigate the reduction in the aerodynamic drag of a vehicle by employing a dimpled non-smooth surface. The computational scheme was validated by the experimental data reported in literature. The mechanism and the effect of the dimpled non-smooth surface on the drag reduction were revealed by analysing the flow field structure of the wake. In order to maximize the drag reduction performance of the dimpled non-smooth surface, an aerodynamic optimization method based on a Kriging surrogate model was employed to design the dimpled non-smooth surface. Four structure parameters were selected as the design variables, and a 16-level design-of-experiments method based on orthogonal arrays was used to analyse the sensitivities and the influences of the variables on the drag coefficient; a surrogate model was constructed from these. Then a multi-island genetic algorithm was employed to obtain the optimal solution for the surrogate model. Finally, the surrogate model and the simulation results showed that the optimal combination of design variables can reduce the aerodynamic drag coefficient by 5.20%.

Aerodynamic Drag Reduction of SUV Based on Underbody Cover Board

2014 ◽  
Vol 602-605 ◽  
pp. 477-480
Author(s):  
Jing Yu Wang ◽  
Bao Yu Wang ◽  
Xing Jun Hu ◽  
Lei Liao
Keyword(s):  
Flow Field ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Flow Line ◽  
Wind Tunnel Test ◽  
Aerodynamic Performance ◽  
Simulation Based ◽  
Aerodynamic Drag Coefficient ◽  
Aerodynamic Drag Reduction

The principles and method of computational fluid dynamics were applied to numerical simulate the external flow field about the SUV model. The hybrid mesh of tetrahedral and triangular prismatic as well as the turbulence model of Realizable k-ε was adopted to study the flow field of SUV of flat underground. Then the SUV of complex underground was simulated with the same mesh strategy and boundary condition. The aerodynamic drag coefficient of latter was bigger than former. That illuminated the complex underground has affect to aerodynamic performance of vehicle. The wind tunnel test validated the veracity of numerical simulation. Based on that, the underground cover board was appended; the aerodynamic drag coefficient was depressed. The velocity and pressure distribution and flow line were achieved. The conclusions provide theoretical reference for the further study of aerodynamic drag reduction of complex underground.

A new moving model test method for the measurement of aerodynamic drag coefficient of high-speed trains based on machine vision

2017 ◽  
Vol 232 (5) ◽  
pp. 1425-1436 ◽  
Author(s):  
Zhiwei Li ◽  
Mingzhi Yang ◽  
Sha Huang ◽  
Dan Zhou
Keyword(s):  
Machine Vision ◽  
Drag Coefficient ◽  
Model Test ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Full Scale ◽  
Test Method ◽  
Test Accuracy ◽  
Friction Resistance ◽  
Aerodynamic Drag Coefficient

A moving model test method has been proposed to measure the aerodynamic drag coefficient of a high-speed train based on machine vision technology. The total resistance can be expressed as the track friction resistance and the aerodynamic drag according to Davis equation. Cameras are set on one side of the track to capture the pictures of the train, from which the line marks on the side surface of the train are extracted and analyzed to calculate the speed and acceleration of the train. According to Newton’s second law, the aerodynamic drag coefficient can be resolved through multiple tests at different train speeds. Comparisons are carried out with the full-scale coasting test, wind tunnel test, and numerical simulation; good agreement is obtained between the moving model test and the full-scale field coasting test with difference within 1.51%, which verifies that the method proposed in this paper is feasible and reliable. This method can accurately simulate the relative movement between the train, air, and ground. The non-contact measurement characteristic will increase the test accuracy, providing a new experimental method for the aerodynamic measurement.

scholarly journals Numerical Study of the Generic Sports Utility Vehicle Design with a Drag Reduction Add-On Device

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Shubham Singh ◽  
M. Zunaid ◽  
Naushad Ahmad Ansari ◽  
Shikha Bahirani ◽  
Sumit Dhall ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Fuel Efficiency ◽  
Ansys Fluent ◽  
Mean Pressure ◽  
Aerodynamic Drag Coefficient ◽  
Total Base ◽  
Aerodynamic Parameters

CFD simulations using ANSYS FLUENT 6.3.26 have been performed on a generic SUV design and the settings are validated using the experimental results investigated by Khalighi. Moreover, an add-on inspired by the concept presented by Englar at GTRI for drag reduction has been designed and added to the generic SUV design. CFD results of add-on model and the basic SUV model have been compared for a number of aerodynamic parameters. Also drag coefficient, drag force, mean surface pressure, mean velocities, and Cp values at different locations in the wake have been compared for both models. The main objective of the study is to present a new add-on device which may be used on SUVs for increasing the fuel efficiency of the vehicle. Mean pressure results show an increase in the total base pressure on the SUV after using the device. An overall reduction of 8% in the aerodynamic drag coefficient on the add-on SUV has been investigated analytically in this study.

Numerical Optimization Research on Rear Characteristic Angles Based on MIRA Model for Aerodynamic Drag Reduction

2013 ◽  
Vol 774-776 ◽  
pp. 428-432
Author(s):  
Qian Qian Du ◽  
Xing Jun Hu ◽  
Qi Fei Li ◽  
Yu Kun Liu ◽  
Bo Yang
Keyword(s):  
Inclination Angle ◽  
Numerical Optimization ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Optimization Method ◽  
Aerodynamic Design ◽  
Rear Window ◽  
Passenger Car ◽  
Two Parameters ◽  
Aerodynamic Drag Reduction

The rear characteristic angles of the passenger car in this study were defined as the inclination angle of rear window and the bottom inclination angle of aft based on the MIRA model. The numerical optimization method was used to analyze the influence of combined variation of two angles on the external flow field and the CD of the passenger car, in which we combined genetic algorithm with the CFD simulation to reduce aerodynamic drag by seeking the relatively optimal combination of two parameters above. The study reveals that when the combination of the inclination angle of rear window and bottom inclination angle of aft is 25oand 0.067o, the total pressure and streamline distribution in the flow fields of the MIRA model are improved greatly and the CD is reduced compared with the worst combination. This conclusion will have profound guiding significance in the aerodynamic design of the rear styling and shape of a car.

scholarly journals Drag Reduction on car side mirrors with the implementation of camera modules

2021 ◽  
Author(s):  
Mahmud Hasan ◽  
Jeffrey Yokota
Keyword(s):  
Solid State ◽  
Drag Reduction ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
The Other ◽  
Aerodynamic Forces ◽  
Fuel Prices ◽  
Entire Vehicle ◽  
Maximum Decrease ◽  
Total Vehicle

The greatest obstacle in the acceleration of a car through air is aerodynamic drag. With this increased drag is the expenditure of fuel. About 50-60% of a vehicles’ total fuel energy is lost to overcome adverse aerodynamic forces. However, with the increase of fuel prices, many solutions have surfaced. One of these solutions are the implementation of camera modules to replace bulky traditional side mirrors. For this report, a thorough analysis was conducted into the aerodynamic benefits of these newly proposed camera modules in comparison to the conventional solid state mirrors. Specifically, one conventional side mirror along with two newly proposed camera module’s were studied in this thesis report. For this analysis, the overall drag of each module was found using CFD simulation under turbulent conditions at 60 km/h using the Realized K- method. The drag and Cd values found for the conventional side mirror were 3.985 N and 0.38 respectively. The values found for the two camera modules, Models B and C, were 0.526 N and 0.857 N. Their Cd values were found to be 0.312 and 0.365. This shows a potential of the drag reduction of the side mirror by almost 87% if the switch was made to the newer technology. This value also agreed with the prediction by Honda on their technology which has stated a possible drag reduction for this part by up to 90%. However, when observing the bigger picture, it became evident that although this drag reduction is significant for locally, it simply is not enough to make a big impact on the drag reduction of the entire vehicle. With a maximum decrease in the total vehicle drag found to to be only 4%, the reduction in the fuel consumption of the vehicle would only decrease by 0.2 gallons per mile. On the other hand, improvements in parts such as the car rims or the underbelly of the car can result in fuel improvements of upwards of 12%-25%. For this reason, it can be concluded that automobile manufacturers research other possible solutions to reduce the vehicle drag such as with the redesign of the underbelly of the car or wheel arches and rims.

Investigation of effects of tire contour on aerodynamic characteristics and its optimization

2021 ◽  
pp. 095440702110586
Author(s):  
Lingxin Zhang ◽  
Haichao Zhou ◽  
Guolin Wang ◽  
Huiyun Li ◽  
Qingyang Wang
Keyword(s):  
Aerodynamic Drag ◽  
Great Influence ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Design Parameters ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Design Variables ◽  
Aerodynamic Drag Coefficient ◽  
Contour Design

Reducing the aerodynamic drag is one of the most important approaches for the development of energy-saving and environment-friendly automobiles. The tire contour has a great influence on the aerodynamic characteristics of automobiles. The aim of this study is to investigate the influence of the tire contour design parameters on the aerodynamic characteristics around a closed wheel, and obtain the optimized tire contour to reduce the automobile aerodynamic drag. A passenger car tire 185/65R14 was selected to conduct the wind tunnel test, and the surface pressure coefficients were used to validate the simulation model established using the detached eddy simulation (DES) model. To decrease tire drag, and taking the upper sidewall height, the tread radii, the tread width, and the transition arc radius of the shoulder as four design variables of contour, a combination of the Latin hypercube experimental design, the Kriging surrogate model, and the adaptive simulated annealing (ASA) algorithm were used to optimize the tire contour design parameters. The changes of flow field around the tire, including the velocity, turbulent kinetic energy, and pressure field were compared and analyzed for further understanding of the drag reduction mechanism. It is found that the aerodynamic drag coefficient of the optimized tire is reduced by 14.5%, and the aerodynamic coefficient drag of the car using the optimized tire is reduced by 7%. The present results are expected to provide useful information for designing new tire structures and improving the aerodynamic performance of the automobile.

HELICAL TWISTED EFFECT OF SPIRAL PIPE IN GENERATING SWIRL FLOW FOR COAL SLURRIES CONVEYANCE

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Yanuar Yanuar ◽  
Kurniawan T. Waskito ◽  
Sealtial Mau ◽  
Winda Wulandari ◽  
Sri P. Sari
Keyword(s):  
Drag Reduction ◽  
Cfd Simulation ◽  
Flow Characteristics ◽  
Solid Material ◽  
Swirl Flow ◽  
Solid Particles ◽  
Test Loop ◽  
Helical Angle ◽  
Reduce Energy Consumption ◽  
Set Up

This paper proposes methods to reduce energy consumption for the transportation of coal slurries. Spiral pipe is one of the methods that can improve drag reduction at certain velocity as well as prevent decomposition at the pipe bottom and generate homogenous particles distribution. The objective is to investigate the influence of using spiral pipe to pressure drop and homogeneity of coal slurries. The pipe angles (β) are 140, 230, 400 and 560, the pipe test loop is set up with entrance length 3000 mm. Pressure Transducer and pitot tube are used in the measurements. Percentage of the particle concentrations are varied by weight of 30 %, 40 % and 50 %. The helical angle gives significant effect to eliminate decomposition at the pipe bottom. At CW 50 %, homogeneity of the slurries can reach around 96 % at helical angle 230, It means the mixture between solid material and water more uniform, using circular pipe the homogeneity is only 74 %. Weight concentration of the solid particles and Reynolds number gives significant effect to the drag reduction. Flow of CW =50 % slurry at Re~5x104 through 23° spiral pipe can increase drag reduction by about 30%. Velocity profiles were obtained from numerical CFD simulation validated experimental results make clear the flow characteristics.

Analysis and optimization of a butterfly valve disc

2009 ◽  
Vol 223 (2) ◽  
pp. 81-89 ◽  
Author(s):  
X G Song ◽  
L Wang ◽  
Y C Park
Keyword(s):  
Surrogate Model ◽  
Flow Characteristics ◽  
Kriging Model ◽  
Optimization Method ◽  
Control Device ◽  
Cfd Analysis ◽  
Butterfly Valve ◽  
Pressure Loss Coefficient ◽  
Flow Control Device ◽  
Valve Disc

A butterfly valve is a type of flow control device, which is widely used to regulate a fluid flowing through a section of pipe. Currently, analyses and optimization are of special important in the design and usage of butterfly valves. For the analysis, finite element method (FEM) is often used to predict the safety of valve disc, and computational fluid dynamics (CFD) is commonly used to study the flow characteristics of valve. However, it is difficult to obtain accurate results for the optimization of butterfly valve due to the high non-linearities. For this reason, metamodels or surrogate model methods are extensively employed. This paper integrates metamodel with FEM and CFD analysis to optimize a traditional butterfly valve, where the weight of the valve disc is the design objective, and the strength safety of disc and the pressure loss coefficient of valve are constraints. Kriging model is employed as a surrogate model to formulate the objectives and constrains, and the orthogonal array is used as design of experiment to sample the computer analysis. The optimum results with the corresponding variable combinations for the valve disc are obtained easily by this method. Moreover, the structural and fluid analyses with the obtained optimum variable combinations are conducted again to verify the accuracy of the optimization method. The results demonstrate the capability and potential of this method, which integrates the Kriging model with FEM and CFD analysis, in solving the optimization of a butterfly valve.

Aerodynamic Numerical Simulation in the Process of Car Styling

2009 ◽  
Vol 16-19 ◽  
pp. 862-865 ◽  
Author(s):  
Ying Chao Zhang ◽  
Zhe Zhang ◽  
Shuang Hu Luo ◽  
Jian Hua Tian
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Automotive Industry ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Aerodynamic Design ◽  
Aerodynamic Analysis ◽  
Stability Performance ◽  
Aerodynamic Drag Coefficient ◽  
Velocity Contour

With the development of automotive industry of China, more and more new cars are brought out. Then more and more stylists and engineers will take part in car styling to design new car. In the process of car styling, Car aerodynamics is important to its performance. Especially for more excellent handling and stability performance, more aerodynamic analysis and optimization should been done. At first it was introduced that the process of car styling in this paper. The functions of aerodynamics in the process were indicated. Secondly some ways of aerodynamic analysis were put forward. The first one is wind tunnel test and the second one called virtual wind tunnel test. The virtual wind tunnel test is one of the best modern ways of aerodynamic design which apply in the fields of aerodynamic research widely. It was based on computational fluid dynamics. The details of the virtual wind tunnel test simulation were narrated in this paper. Applying the virtual wind tunnel test aerodynamic drag coefficient, velocity contour and pressure distribution were got. Some advices to reduce aerodynamic drag of the design car were put forward. In one word, it is one simple, effective, convenient and fast way for aerodynamic design in car styling process using virtual wind tunnel test.

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