Controlling Drag and Down Forces on a Vehicle Side-View Mirror by Applying Vortex Generator Designs on the Bottom Surface

2020 ◽  
Author(s):  
Zulong Dong ◽  
Badih Jawad ◽  
Liping Liu ◽  
Hossam Metwally
Keyword(s):  
Drag Force ◽  
Flow Separation ◽  
Flow Behavior ◽  
Aerodynamic Performance ◽  
Vehicle Body ◽  
Bottom Surface ◽  
Cfd Analysis ◽  
Side View ◽  
Baseline Model ◽  
Back Edge

Abstract Side-view mirrors impact the aerodynamic performance of a vehicle due to the creation of extra drag force, noise, and vibration. This paper presents an alternative practical solution for improving aerodynamic performance of vehicle side-view mirrors. A CFD analysis is conducted for studying the airflow around a side-view mirror with different types of passive vortex generators (VGs) mounted on the bottom surface. VGs are small wingtips that are used to produce swirling motion in the flow stream. In recent years, VGs have been used in vehicle underbody diffusers to delay flow separation and to increase the flow control surface. This study aims to understand the effect of underbody VGs on the flow mechanisms downstream of the side-view mirror, and its impact on both drag and down forces. The turbulent flow behind the side-view mirror is investigated to determine the effects of different VG types and attack angles. Four types of VGs are considered in this work. Changes are made to the baseline model by either adding the VGs close to the frontal edge of the bottom surface of the mirror which aims to control the flow separation, or adding the VGs close to the back edge which aims to reduce the shedding area. Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent is conducted to simulate the flow behavior by using three dimensional Reynolds-averaged Navier-Stokes method with standard K-epsilon (K-ε) turbulence model. In order to incorporate the effect of vehicle body, each model is assembled on a quad-vehicle bluff body for analysis. The drag and down forces are numerically solved and compared with the results of the baseline model at the speeds of 15, 40, 60 and 80 miles per hour. It is concluded from the CFD analysis that: (1) Mounting VGs at the bottom surface of a side-view mirror reduces down force in most cases. (2) Setting underbody VGs at either the front or back edge of the mirror bottom surface has a slight effect on reducing drag force. (3) Multiple types of VGs show improved results with a 30 degree attack angle, which encourages future studies of VG applications with large attack angles.

Vortex Generator Designs to Improve Flow for a Vehicle Side-View Mirror

2019 ◽  
Author(s):  
Zulong Dong ◽  
Badih Jawad ◽  
Liping Liu ◽  
Hossam Metwally
Keyword(s):  
Drag Force ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Cfd Analysis ◽  
Side View ◽  
Baseline Model ◽  
Force Increase ◽  
Flow Improvement

Abstract The unsteady airflow over automotive side-view mirrors is a typical source of turbulence which creates extra drag force, aerodynamic noise and vibration. A CFD analysis is presented for vortex generators (VGs) application on the vehicle side-view mirrors for the purpose of flow improvement. Vortex generators are used to delay flow separation and increase the control surfaces which affect the drag force and down force of the vehicle. Reduced drag force can potentially increase fuel economy, and an increased downforce will increase vehicle grip force and improve vehicle stability which is essential for racing cars. This paper presents practical solutions for mitigating flow turbulence and adjusting down force for existing side-view mirrors. Four VG configurations were designed and numerically analyzed in combination with the baseline model at air speeds ranged from 15 to 80 miles per hour. This research investigated the effect of each VG configuration on the side-view mirror’s aerodynamic performance. The turbulent flow through the side-view mirror were analyzed by using standard K-epsilon (K-ε) Reynolds-averaged Navier-Stokes method. The drag and down forces results were obtained and compared with the baseline model. The CFD analysis concluded the following: (1) Setting the VGs with a 5 degree attack angle on the upwind face of the mirror slightly reduced the drag force. (2) Setting the VGs at the top of the mirror surface greatly increased the downforce with a large drag force increase.

A Combined Application of Negative Bowed Blade and Endwall Unsteady Pulsed Holed Suction in a Highly Loaded Compressor Cascade

2018 ◽  
Author(s):  
Shaowen Chen ◽  
Hongxin Zhang ◽  
Qinghe Meng ◽  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Flow Behavior ◽  
Excitation Frequency ◽  
Aerodynamic Performance ◽  
Flow Ratio ◽  
Compressor Cascade ◽  
Aero Engine ◽  
Suction Flow ◽  
Highly Loaded

With the increasing continually of blade load, a serious three-dimensional (3D) unsteady flow separation is caused in the design of modern advanced aero-engine compressor. The flow separation has a strong influence on the aerodynamic behavior of the flow in the compressor passage such as reducing the pressure rise capability and overall efficiency, and even resulting in stall and surge. Consequently, it is very necessary to apply some effective techniques for suppressing the 3D flow separation in order to improve the aerodynamic performance of aero-engine compressors. The endwall unsteady pulsed holed suction (EUPHS) is first developed. Additionally, the negative bowed blade is a convention passive flow control method. It can make the flow of the midspan move toward the endwall by changing the radial pressure distribution and improve flow behavior of the midspan. Therefore, with the aim of further improving the aerodynamic performance and flow behavior, the EUPHS combined with the negative bowed blade as a new promising compound flow control (CFC) technique is proposed. In this study, only two bleeding holes on the endwalls (one on the upper endwall and another on the lower endwall) are used to achieve suction in a highly loaded compressor cascade. The improvements in aerodynamic performance by endwall steady constant holed suction (ESCHS), EUPHS and CFC are investigated and compared firstly. Some related parameters such as suction-to-inlet time-averaged suction flow ratio and excitation frequency are also discussed and analyzed in detail. The results show that CFC has more potential advantages than ESCHS and EUPHS in reducing the total pressure loss coefficient and is a promising flow control technology to further enhance aerodynamic performance. Based on the optimal suction-to-inlet time-averaged suction flow ratio and excitation frequency, the total pressure loss coefficients for CFC are reduced by 17.7%.

Effects of Tire Attributes on Aerodynamic Performance

2020 ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Experimental Testing ◽  
Side Wall ◽  
Sensitivity Study ◽  
Aerodynamic Performance ◽  
Baseline Model ◽  
Design Changes ◽  
Boundary Condition Method ◽  
Wall Profile

Abstract As indicated by previous studies, many attributes of tires have been shown to have an impact on tire aerodynamic drag. However, the way these attributes affect tire aerodynamics has not been systematically investigated to date. It is not clear which tire attributes have the most significant impact on aerodynamic drag. Therefore, a sensitivity study of the effects of tire attributes on tire aerodynamic performance is proposed in this study. This sensitivity study improves the understanding of flow structures and mechanisms around tires. First, a baseline CFD model of a tire is created and validated by experimental data. In the computational model, the tire is positioned in a wind tunnel to match the experimental testing configuration. A hybrid boundary condition method is used to simulate a rotating tire. Based on the validated baseline model, various tire attributes are considered and compared in the study proposed. The tire attributes considered include tire width, tire side wall profile, lateral grooves, and open rim design. There are five cases in total for the sensitivity study. Then the effects of these attributes on the tire aerodynamic drag are calculated and compared. The most influencing feature is then identified. The results show that a smoothed side wall profile with smaller radius can improve the aerodynamic performance of an isolated tire. On the other hand, the influence of lateral grooves on tire aerodynamic performance is limited. The force integrated from all lateral groove surfaces only account to less than 2% of the total tire drag force. Additionally, an idealized open rim design changes the flow structure significantly, which leads to the increase of aerodynamic drag. The force integrated on the rim surface account for up to 20% of the overall tire drag force.

Computer-Aided Front and Rear Wings Aerodynamic Design of a Formula SAE Racing Car

2011 ◽  
Vol 120 ◽  
pp. 20-25 ◽  
Author(s):  
Mei Nan Chen ◽  
Wen Hui Tang ◽  
Bo Yang ◽  
Xing Jun Hu
Keyword(s):  
Aerodynamic Performance ◽  
Vehicle Body ◽  
Cfd Analysis ◽  
Aerodynamic Design ◽  
Formula Sae ◽  
Dynamic Events ◽  
Rear Wing ◽  
Computational Fluid Dynamics Analysis ◽  
Final Design ◽  
Front Wing

The objective of this research is to design a set of front and rear wings that can help maximize the down-force to enhance the aerodynamic performance of 2011 Jilin University Formula SAE racing car in dynamic events. In this research, computational fluid dynamics analysis is used for the design of the front and rear wings. Based on a given vehicle body styling, twenty sets of front wing and rear wing profile are investigated, the influence of the endplate shape on the wing aerodynamic performance is also investigated, and one plan was chosen as final design, which is suitable for the vehicle at a relatively low speed (70km/h). The CFD analysis results show that the suitable front wing and rear wing will enhance the aerodynamic performance of the racing car significantly.

Experimental study of a pitching and plunging wing

2018 ◽  
Vol 90 (7) ◽  
pp. 1136-1144 ◽  
Author(s):  
Dimitris Gkiolas ◽  
Demetri Yiasemides ◽  
Demetri Mathioulakis
Keyword(s):  
Experimental Data ◽  
Flow Visualization ◽  
Wind Turbine ◽  
Flow Separation ◽  
Flow Behavior ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Content Type ◽  
Separation Line ◽  
Wing Chord

Purpose The complex flow behavior over an oscillating aerodynamic body, e.g. a helicopter rotor blade, a rotating wind turbine blade or the wing of a maneuvering airplane involves combinations of pitching and plunging motions. As the parameters of the problem (Re, St and phase difference between these two motions) vary, a quasi-steady analysis fails to provide realistic results for the aerodynamic response of the moving body, whereas this study aims to provide reliable experimental data. Design/methodology/approach In the present study, a pitching and plunging mechanism was designed and built in a subsonic closed-circuit wind tunnel as well as a rectangular aluminum wing of a 2:1 aspect-ratio with a NACA64-418 airfoil, used in wind turbine blades. To measure the pressure distribution along the wing chord, a number of fast responding transducers were embedded into the mid span wing surface. Simultaneous pressure measurements were conducted along the wing chord for the Reynolds number of 0.85 × 106 for both steady and unsteady cases (pitching and plunging). A flow visualization technique was used to detect the flow separation line under steady conditions. Findings Elevated pressure fluctuations coincide with the flow separation line having been detected through surface flow visualization and flattened pressure distributions appear downstream of the flow separation line. Closed hysteresis loops of the lift coefficient versus angle of attack were measured for combined pitching and plunging motions. Practical implications The experimental data can be used for improvement of unsteady fluid mechanics problem solvers. Originality/value In the present study, a new installation was built allowing the aerodynamic study of oscillating wings performing pitching and plunging motions with prescribed frequencies and phase lags between the two motions. The experimental data can be used for improvement of computational fluid dynamics codes in case that the examined aerodynamic body is oscillating.

scholarly journals Aerodynamic Performance of Road Vehicles

2020 ◽  
Vol 9 (6) ◽  
pp. 642-645
Keyword(s):  
Wind Tunnel ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Aerodynamic Performance ◽  
Polished Surface ◽  
Anova Analysis ◽  
Road Vehicles ◽  
Car Model ◽  
Group Data ◽  
Scale Models

Aerodynamic drag has been experimentally estimated for scale models of a passenger car and a commercial truck in a wind tunnel. Polished surface has resulted up to 15 % reduction in drag force and add-on has resulted in 57% increase in drag force of a car model whereas 2.6 % reduction in drag force has resulted by using deflector in a commercial truck model. Anova analysis shows variation in mean of group data.

Aerodynamic Investigation of Double Surface Airfoil

2021 ◽  
Vol 1 (2) ◽  
pp. 41-46
Author(s):  
Siva J ◽  
Suresh C ◽  
Paramaguru V
Keyword(s):  
Experimental Investigation ◽  
Flow Separation ◽  
Research Work ◽  
Aerodynamic Performance ◽  
Aircraft Industry ◽  
Aerodynamic Efficiency ◽  
Flight Vehicles ◽  
Double Surface ◽  
Naca 0012 ◽  
Aerodynamic Investigation

Aircraft industry has been deeply concerned about reduction of drag by reducing flow separation and improving the aerodynamic efficiency of flight vehicles, particularly in commercial and military market by adopting various methods. Reduction of flow separation is a concept by which we can increase aerodynamic efficiency. The purpose of the project is to perform an experimental investigation on aerodynamic performance of NACA 0012 airfoil model with and without splits. It is evident from this research work that the airfoil model with split possesses greater aerodynamic performance by producing lesser overall drag. This is due to the delay in flow separation from the surface.

scholarly journals Effect of Single-Row and Double-Row Passive Vortex Generators on the Deep Dynamic Stall of a Wind Turbine Airfoil

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2535
Author(s):  
Chengyong Zhu ◽  
Tongguang Wang ◽  
Jie Chen ◽  
Wei Zhong
Keyword(s):  
Wind Turbine ◽  
Flow Separation ◽  
Aerodynamic Performance ◽  
Vortex Generators ◽  
Dynamic Stall ◽  
Aerodynamic Forces ◽  
Double Row ◽  
Single Row ◽  
Maximum Angle ◽  
Wind Turbine Airfoil

Passive vortex generators (VGs) have been widely applied on wind turbines to boost the aerodynamic performance. Although VGs can delay the onset of static stall, the effect of VGs on dynamic stall is still incompletely understood. Therefore, this paper aims at investigating the deep dynamic stall of NREL S809 airfoil controlled by single-row and double-row VGs. The URANS method with VGs fully resolved is used to simulate the unsteady airfoil flow. Firstly, both single-row and double-row VGs effectively suppress the flow separation and reduce the fluctuations in aerodynamic forces when the airfoil pitches up. The maximum lift coefficient is therefore increased beyond 40%, and the onset of deep dynamic stall is also delayed. This suggests that deep dynamic-stall behaviors can be properly controlled by VGs. Secondly, there is a great difference in aerodynamic performance between single-row and double-row VGs when the airfoil pitches down. Single-row VGs severely reduce the aerodynamic pitch damping by 64%, thereby undermining the torsional aeroelastic stability of airfoil. Double-row VGs quickly restore the decreased aerodynamic efficiency near the maximum angle of attack, and also significantly accelerate the flow reattachment. The second-row VGs can help the near-wall flow to withstand the adverse pressure gradient and then suppress the trailing-edge flow separation, particularly during the downstroke process. Generally, double-row VGs are better than single-row VGs concerning controlling deep dynamic stall. This work also gives a performance assessment of VGs in controlling the highly unsteady aerodynamic forces of a wind turbine airfoil.

Numerical Study on Film Foam Flow Characteristics in a Straight Duct

2013 ◽  
Vol 561 ◽  
pp. 472-477 ◽  
Author(s):  
Dong Xing Du ◽  
Fa Hu Zhang ◽  
Dian Cai Geng ◽  
Ying Ge Li
Keyword(s):  
Drag Force ◽  
Pressure Difference ◽  
Numerical Study ◽  
Flow Behavior ◽  
Petroleum Industry ◽  
Flow Characteristics ◽  
Viscous Force ◽  
Ideal Condition ◽  
Surface Evolver ◽  
The Mathematical Model

Straight ducts capture some essential features of the motion of foam in porous media in petroleum industry. In this paper, Surface Evolver was employed to build the mathematical model to study the flow behavior of lamellas in the duct with different models. Numerical results show good agreement with experiments and some important features of lamella flow behavior in straight ducts are obtained. It is concluded that, the physical model with viscous force can adequately describe the flow characteristics of reality foam in the experiment. The actual pressure difference consists of the pressure difference caused by the curvature of the lamellas and the drag force on the boundary wall. Under the ideal condition of without drag force along the wall, the pressure drop for lamella flow in the duct is zero, and the shape and the velocity of the lamellas will maintain constant.

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