scholarly journals An overview of passive and active drag reduction methods for bluff body of road vehicles

2018 ◽  
Vol 7 (4.13) ◽  
pp. 53
Author(s):  
Lay Chuan Eun ◽  
Azmin Shakrine Mohd Rafie ◽  
Surjatin Wiriadidjaja ◽  
Omar Faruqi Marzuki
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Smooth Surface ◽  
Bluff Body ◽  
Rotation Speed ◽  
Rotating Cylinder ◽  
Road Vehicles ◽  
Reduction Methods ◽  
Base Drag ◽  
Active Drag

This paper is an overview of results done on bluff body road vehicle’s base drag reduction either by experimental or numerical methods. Two categories of devices are divided that prove certain degrees of effectiveness in reducing the base drag, namely passive and active. The reduction of drag coefficient achieved in existing research ranging from 5% to 50%, which varies for each method and device. However, the higher the achieved drag reduction is, the greater the compensation required is. The compensation comes in various forms to achieve the desirable drag reduction. For passive drag reduction, hump shaped bluff body with boat-tail shows significant drag reduction by 50.9% compared to the other methods. Meanwhile, one of the potential of active drag reductions is by utilizing rotating cylinder. The rotating can reduce the drag on the bluff body by influencing the separation of boundary layer. The drag can be further reduced by enhancing the rotating cylinder with surface roughness and rotation speed. A notable 23% reduction of drag coefficient using rough surface on bluff body vehicle’s is achieved compared to the smooth surface.  

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%.

Recent Advances in Wake Dynamics and Active Drag Reduction of Simple Automotive Bodies

2021 ◽  
Author(s):  
Yu Zhou ◽  
Bingfu Zhang
Keyword(s):  
Machine Learning ◽  
Drag Reduction ◽  
Closed Loop ◽  
Three Dimensional ◽  
The Body ◽  
Flow Structures ◽  
Slant Angle ◽  
Reduction Mechanisms ◽  
Reduction Methods ◽  
Active Drag

Abstract This is a compendium of recent progresses in the development of wake dynamics and active drag reduction of three-dimensional simple automotive models, largely focused on the generic Ahmed body. It covers our new understanding of involved instabilities, predominant frequencies, pressure distribution and unsteady flow structures in the high- (12.5° < f < 30°) and low-drag (f > 30°) bodies and the square-back body (f = 0°), where f is the rear slant angle of the body. Various drag reduction methods and their performances are reviewed, including open- and closed-loop controls along with machine-learning control. The involving drag reduction mechanisms, net saving and efficiencies are discussed. Comments are made for the areas that deserve more attention and future investigation.

Analysis of the Drag Reduction Using Vortex Kinematics Behind a Bluff Body

2010 ◽  
Author(s):  
Charles-Henri Bruneau ◽  
Emmanuel Creuse´ ◽  
Delphine Depeyras ◽  
Patrick Gillie´ron ◽  
Iraj Mortazavi
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Active Control ◽  
Bluff Body ◽  
Strong Relationship ◽  
Back Wall ◽  
Control Processes ◽  
Drag Forces ◽  
Vortex Kinematics

The aim of this work is to analyse one of the mechanisms that contributes to the drag forces, namely the distance of the vortices to the back wall of a bluff body. The study shows the strong relationship between this distance and the pressure forces at the back. Indeed, the active control processes modify the trajectory of the vortices to accelerate their removal from the wall and consequently reduce the drag coefficient.

Drag reduction of 3D bluff body using SDBD plasma actuators

2020 ◽  
pp. 095440702096189
Author(s):  
Mostafa Kazemi ◽  
Parisa Ghanooni ◽  
Mahmoud Mani ◽  
Mohammad Saeedi
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Bluff Body ◽  
Separation Bubble ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Force Balance ◽  
Plasma Actuators ◽  
Laminar Separation ◽  
Trailing Vortices

In the current research, a series of different combinations of plasma SDBD actuators mounted on a simplified road vehicle have been experimentally studied to find the optimum position of the actuators for controlling the flow separation and reducing the vehicle form drag. Separation point of the flow over the rear ramp, large trailing vortices of the standard model, and laminar separation bubble (LSB) of the rear ramp leading edge are among the most significant factors to be controlled. The experiments were conducted at Reynolds numbers ranging from 0.55 × 106 to 1.11 × 106 in a subsonic wind tunnel while the pressure distribution over the model and its streamwise force balance were accurately measured. Significant drag reduction due to the use of DBD actuators was observed. As such, for the range of tested Reynolds numbers, a maximum of 25.1% of drag reduction in the vehicle drag coefficient could be achieved. The optimum combinations of activation voltages (6, 9, and 12 kV) and wave frequencies (6, 10, and 14 kHz) for plasma actuators were also found. Furthermore, it was observed that SDBD actuators mounted on the rear ramp of the model had a deeper impact on the vehicle drag coefficient compared to the other actuators.

Base drag reduction concept for commercial road vehicles

Energy ◽  
2020 ◽  
Vol 205 ◽  
pp. 118075
Author(s):  
Jędrzej Mosiężny ◽  
Bartosz Ziegler ◽  
Przemysław Grzymisławski ◽  
Rafał Ślefarski
Keyword(s):  
Drag Reduction ◽  
Road Vehicles ◽  
Base Drag

scholarly journals Base Drag Reduction of 2D Bluff Body by Using Tabs at Transonic Speeds

2008 ◽  
Vol 56 (648) ◽  
pp. 15-21
Author(s):  
Atsushi Hashimoto ◽  
Takahiro Kobayashi ◽  
Yoshiaki Nakamura
Keyword(s):  
Drag Reduction ◽  
Bluff Body ◽  
Base Drag

Effect of Slit Inclusions in Drag Reduction of Flow over Cylinders

2016 ◽  
Vol 846 ◽  
pp. 18-22
Author(s):  
Rohit Bhattacharya ◽  
Abouzar Moshfegh ◽  
Ahmad Jabbarzadeh
Keyword(s):  
Fluid Flow ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Finite Volume ◽  
Lattice Boltzmann ◽  
Circular Cross Section ◽  
Finite Volume Methods ◽  
Turbulent Regime ◽  
Ansys Fluent ◽  
Comparison Of The Results

The flow over bluff bodies is separated compared to the flow over streamlined bodies. The investigation of the fluid flow over a cylinder with a streamwise slit has received little attention in the past, however there is some experimental evidence that show for turbulent regime it reduces the drag coefficient. This work helps in understanding the fluid flow over such cylinders in the laminar regime. As the width of the slit increases the drag coefficient keeps on reducing resulting in a narrower wake as compared to what is expected for flow over a cylinder. In this work we have used two different approaches in modelling a 2D flow for Re=10 to compare the results for CFD using finite volume method (ANSYS FLUENTTM) and Lattice Boltzmann methods. In all cases cylinders of circular cross section have been considered while slit width changing from 10% to 40% of the cylinder diameter. . It will be shown that drag coefficient decreases as the slit ratio increases. The effect of slit size on drag reduction is studied and discussed in detail in the paper. We have also made comparison of the results obtained from Lattice Boltzmann and finite volume methods.

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