scholarly journals Experimental and Numerical Investigations on the Influence of Vehicle Rear Diffuser Angle on Aerodynamic Drag and Wake Structure

2011 ◽  
Vol 2 (2) ◽  
pp. 47-53 ◽  
Author(s):  
Chenguang Lai ◽  
Yasuaki Kohama ◽  
Shigeru Obayashi ◽  
Shinkyu Jeong
Keyword(s):  
Aerodynamic Drag ◽  
Wake Structure ◽  
Numerical Investigations ◽  
Diffuser Angle

Experimental and numerical investigations of the vehicle aerodynamic drag with single-channel rear diffuser

2020 ◽  
Vol 234 (8) ◽  
pp. 2216-2227 ◽  
Author(s):  
Huang Taiming ◽  
Zhuang Xiaodong ◽  
Wan Zhongmin ◽  
Gu Zhengqi
Keyword(s):  
Single Channel ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Aerodynamic Performance ◽  
Channel Width ◽  
Structure Parameters ◽  
Reduction Mechanism ◽  
Numerical Investigations ◽  
Diffuser Angle ◽  
The Relationship

The main purpose of this paper is to reveal the drag reduction mechanism of single-channel rear diffuser on the vehicle aerodynamic drag and to obtain the relationship between the structure parameters of rear diffuser and the vehicle aerodynamic drag. The influence of the single-channel rear diffuser on the aerodynamic drag is studied using the Reynolds-averaged method with the 25° slant Ahmed model. The accuracy of the numerical method is validated by means of a wind tunnel test. The aerodynamic performance of the Ahmed model with different vertical diffuser angles, lateral diffuser angles, and channel widths is discussed. The results demonstrate that the vortex location will be influenced by the vertical diffuser angle, and with the vortex core approaching to the model, the aerodynamic drag will increase. The aerodynamic drag reaches the minimum value with a vertical diffuser angle of 10.46°. Moreover, the aerodynamic drag decreases with increasing channel width. Finally, the aerodynamic drag can be reduced by 5.3%, when the vertical diffuser angle, lateral diffuser angle, and channel width are 10.46°, 0°, and 351 mm, respectively.

CFD Based Investigations into Optimization of Diffuser Angle on Rear Bus Body

2016 ◽  
Vol 836 ◽  
pp. 127-131 ◽  
Author(s):  
Wawan Aries Widodo ◽  
Mutiara Nuril Karohmah
Keyword(s):  
Fluid Flow ◽  
Lift Force ◽  
Bluff Body ◽  
Cfd Simulation ◽  
Aerodynamic Forces ◽  
Wake Structure ◽  
Bus Body ◽  
Simulation Results ◽  
Drag And Lift ◽  
Diffuser Angle

Fluid flow interaction around bluff body to create aerodynamic forces including drag and lift force. The strategy to improve arodynamic forces to modify the shape of rear body. This investigation is conducted to simulate fluid flow past a bus body with variation of diffuser angle on the rear. The diffuser angle was set to 0°, 6°, 12°, and 18°, respectively. The CFD simulation results shown that diffuser on rear body bus models able to improve the aerodynamic forces and wake structure are correspond with incresing diffuser angle. The drag coefficient was reduced until 2.3% is related with diffuser angle (β) 180, also, diffuser angle (β) 120 capable to increase downforce significantly until ten times are compared with zero diffuser angle.

Influence of Base Slant on the Wake Structure and Drag of Road Vehicles

1983 ◽  
Vol 105 (4) ◽  
pp. 429-434 ◽  
Author(s):  
S. R. Ahmed
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Kinetic Energy ◽  
Aerodynamic Drag ◽  
Energy Content ◽  
Vortex Motion ◽  
Pressure Measurements ◽  
Road Vehicles ◽  
Wake Structure ◽  
Slant Angle

The time averaged wake structure of a realistically dimensioned quarter scale automobile model was studied in a wind tunnel on the basis of flow visualization, wake surveys, force and pressure measurements. Through a systematic variation of base slant angle in the range of 0 to 40 deg, the ensuing changes in the wake structure were observed and the wake structure present at lowest value of aerodynamic drag is shown. Experimental data were obtained at a model length based Reynolds number of 4.29 million. Correlation of wake structure with drag, pressure distribution, and kinetic energy content of vortex motion in wake is addressed.

Effect of Underbody Diffuser on the Aerodynamic Drag of Vehicles in Convoy

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
D.J.S. Aulakh
Keyword(s):  
Transport Model ◽  
Aerodynamic Drag ◽  
Cfd Analysis ◽  
Flow Features ◽  
Ground Conditions ◽  
Shear Stress Transport Model ◽  
Cfd Analyses ◽  
Underbody Diffuser ◽  
Diffuser Angle ◽  
Ahmed Body

Current study examines the effect on coefficient of drag (Cd) of convoy of two reference car bodies (Ahmed body) by employing underbody diffuser on lead body. CFD analysis of convoy is done using Shear-Stress-Transport model under moving ground conditions. The lead body’s diffuser length is taken as 222m with diffuser angle of 0° (no diffuser), 3°, 5, 7°, 9°, 15°, 20°, 25°and 30° each at inter-vehicular 0.25 and 0.75 body length. Each configuration resulting was analyzed with lead body backlite angle of 25° (pre-critical) and 35° (post-critical) with follow body backlite angle remaining 25°. To understand the flow features developed on Ahmed body due to an underbody diffuser a preliminary CFD analysis is done on an isolated body with 25° and 35° backlite angles by applying each diffuser angle in current study. CFD analyses are conducted after performing two validation analyses from previous studies. The drag on lead and follow vehicles was found to also depend on the axial vortices due to diffuser in addition to those from backlite surface of lead body. Average drag on cases with diffuser is found to be lesser than the no diffuser cases up to a certain diffuser angle. Thus applying diffuser has resulted in potential for reducing the overall drag on convoy by deciding optimum configuration.

scholarly journals Design and aerodynamic analysis of an Automotive Adaptive Rear Diffuser

2021 ◽  
Vol 9 (8) ◽  
pp. 1611-1626
Author(s):  
Heet Patel
Keyword(s):  
Fuel Economy ◽  
High Speed ◽  
Electronic Circuit ◽  
Aerodynamic Drag ◽  
Vital Role ◽  
Aerodynamic Forces ◽  
Aerodynamic Efficiency ◽  
Speed Stability ◽  
Diffuser Angle ◽  
Aerodynamic Lift

Abstract: Traditional vehicles are designed to bring out the best performance, good fuel economy, fewer emissions, and good high-speed stability. In this process of designing a vehicle, the underbody geometry of a car plays a vital role and is often neglected because of its complicated design bits. Though the presence of uneven surfaces causes the layers of air to separate resulting in generating turbulence. This report is about designing an active rear diffuser of a car. The rear diffuser is an aerodynamic device that is installed in the end part of the underbody of a car. Diffuser now a day is quite a common aerodynamic device that is used in performance cars. The main moto of attaching a diffuser is to reduce the wake produced behind the car and help the streamlines to converge better. The prime focus of this study is to design an active rear diffuser that will not only help in providing great high-speed stability and aerodynamic efficiency but will also use the aerodynamic forces adversely to help the car stop faster and on its track. This is made possible first by understanding the effects of diffuser angle on the aerodynamic forces acting on the car. Further, to actually transform the computational values into a working model, an electronic circuit is designed which mimics the exact movement of the diffuser according to the speed and other driving conditions. Keywords: Adaptive, diffuser, automobile, aerodynamic, aerodynamic Drag, aerodynamic Lift

Application of Interactive Orthogonal Design on the Aerodynamic Drag Optimization of Hatchback Car

2013 ◽  
Vol 690-693 ◽  
pp. 2703-2707
Author(s):  
Hao Yu ◽  
Hui Zhu ◽  
Zhi Gang Yang
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Orthogonal Design ◽  
Tail Length ◽  
Notable Effect ◽  
Aerodynamic Drag Coefficient ◽  
Diffuser Angle

The interactive orthogonal design was employed to investigate the aerodynamic drag coefficient (CD) of hatchback car by using CFD methods. And the effects of back windshield angle, diffuser angle, front windshield angle, hood angle, side windshield angle and tail length were discussed. The results indicates that back windshield angle, diffuser angle and their interaction, hood angle and front windshield angle have notable effect on the CD of the model, while other parameters and interactions have no notable effect. The best CD conditions are: back windshield angle 20°/60°, diffuser angle 12°, front windshield angle 30°, hood angle 15° and tail length 4300mm.

Investigation of bogie positions on the aerodynamic drag and near wake structure of a high-speed train

2019 ◽  
Vol 185 ◽  
pp. 41-53 ◽  
Author(s):  
Guangjun Gao ◽  
Feng Li ◽  
Kan He ◽  
Jiabin Wang ◽  
Jie Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Aerodynamic Drag ◽  
High Speed Train ◽  
Near Wake ◽  
Wake Structure

Study of Aerodynamic Drag Reduction on a Compact Electric Vehicle

2013 ◽  
Vol 694-697 ◽  
pp. 51-55
Author(s):  
Jia Wang ◽  
Hui Zhu ◽  
Zhi Gang Yang
Keyword(s):  
Electric Vehicle ◽  
Electric Vehicles ◽  
Aerodynamic Drag ◽  
Refined Model ◽  
Vehicle Model ◽  
Front Structure ◽  
Significant Interest ◽  
Aerodynamic Drag Reduction ◽  
Diffuser Angle ◽  
Reducing Energy

Aerodynamic drag of compact electric vehicles is of significant interest in reducing energy consumption. This study focused on how to reduce drag for a compact electric vehicle by shape optimization such as lengthening the tail, changing the front-windshield inclination, modifying the diffuser angle and filling up the front structure details of the vehicle model. Some separately refined models and one integrated refined model were built. The simulation was conducted using the RANS k-epsilon turbulence model by Computational Fluid Dynamics. The results show that nearly every refined model has a lower drag, and the drag coefficient of the integrated refined model has an 8.4% slash compared to the original vehicle model.

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