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Optimization of the Aerodynamic Lift and Drag of LYNK&CO 03+ with Simulation and Wind Tunnel Test

Dassault Systemes(Shanghai) Information Technology Co.-Weiliang Xie, Bo Li, Xiaowei Zhao
Geely Automobile Research Institute-Qian Feng, Biaoneng Luo, Huixiang Zhang, Hong Peng, Zhenying Zhu, Zhi Ding, Ling Zhu
  • Technical Paper
  • 2020-01-0672
To be published on 2020-04-14 by SAE International in United States
Based on the first sedan of the LYNK&CO brand from Geely, a high performance configuration with the additional aerodynamic package was developed. The aerodynamic package including the front wheel deflector, the front lip, the side skirt, the rear spoiler and the rear diffuser, were upgraded to generate enough aerodynamic downforce for better handing stability, without too much compromising of the aerodynamic drag of the vehicle to keep a low fuel consumption. Simulation approach with PowerFLOW, combined with the design space exploration method were used to optimize both of the aerodynamic lift and drag. Wind tunnel test was also used to firstly calibrate the simulation results and finally to validate the optimized design. The results turn out to be appropriate trade-off between the lift and the drag to meet the aerodynamics requirement, and a consistently good matching between the simulation and test.
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Validation Studies for an Advanced Aerodynamic Development Process of Cab-Over Type Heavy Trucks

Exa Corporation-Heinz Friz, Bo Li
FAW R&D Center-Genghua Liao, Shaoyun Sun, Kelong Lu, Qiang Fu, Kecheng Pan
Published 2017-10-25 by SAE International in United States
The implementation of an advanced process for the aerodynamic development of cab-over type heavy trucks at China FAW Group Corporation (FAW) requires a rigorous validation of the tools employed in this process. The final objective of the aerodynamic optimization of a heavy truck is the reduction of the fuel consumption. The aerodynamic drag of a heavy truck contributes up to 50% of the overall resistance and thus fuel consumption. An accurate prediction of the aerodynamic drag under real world driving conditions is therefore very important.Tools used for the aerodynamic development of heavy trucks include Computational Fluid Dynamics (CFD), wind tunnels and track and road testing methods. CFD and wind tunnels are of particular importance in the early phase development. While wind tunnels provide a physical test environment with repeatable conditions their availability is very limited and they also have several other limitations which make it difficult to predict on road performance of the truck. Such limitations are blockage and pressure gradient effects, lack of road simulation and Reynolds number effects. While on the other hand…
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Validation of Aerodynamic Simulation and Wind Tunnel Test of the New Buick Excelle GT

SAE International Journal of Passenger Cars - Mechanical Systems

Exa Corporation-Heinz Friz, Bo Li, Weiliang Xie
Pan Asia Technical Automotive Center Co-Fuliang Wang, Zhangshun Yin, Shi Yan, Jia Zhan
  • Journal Article
  • 2017-01-1512
Published 2017-03-28 by SAE International in United States
The validation of vehicle aerodynamic simulation results to wind tunnel test results and simulation accuracy improvement attract considerable attention of many automotive manufacturers. In order to improve the simulation accuracy, a simulation model of the ground effects simulation system of the aerodynamic wind tunnel of the Shanghai Automotive Wind Tunnel Center was built. The model includes the scoop, the distributed suction, the tangential blowing, the moving belt and the wheel belts. The simulated boundary layer profile and the pressure distribution agree well with test results. The baseline model and multiple design changes of the new Buick Excelle GT are simulated. The simulation results agree very well with test results.
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The Aerodynamic Development of a New Dongfeng Heavy Truck

Dongfeng Commercial Vehicle Company Ltd.-Kebing Tang, Li He, Yao Zhao
Exa Corporation-Heinz Friz, Bo Li
Published 2015-09-29 by SAE International in United States
The development of a new Dongfeng Heavy truck had very strict targets for fuel consumption. As the aerodynamic drag plays a crucial role for the fuel consumption, a low drag value had to be achieved. It was therefore essential to include evaluation and optimization of the aerodynamics in the development process. Because wind tunnel facilities were not available, the complete aerodynamics development was based on digital simulation. The major portion of the aerodynamic optimization was carried out during the styling phase where mirrors, sun visor, front bumper and aero devices were optimized for drag reduction. For optimizing corner vanes and mud guards, self-soiling from the wheel spray was included in the analysis. The aero results did also show that cooling air flow rates are sufficiently high to ensure proper cooling. During the detailed engineering phase an increase of the drag above the target required further optimization work to finally reach the target. Furthermore it was confirmed during this phase with thermal simulations that the design of grille openings, cooling module and fan can meet engine…
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A Coupled Approach to Truck Drum Brake Cooling

Exa Corporation-Sacha Jelic, Bo Li
FAW R&D Center-Shaoyun Sun, Genghua Liao, Qiang Fu, Kelong Lu, Jing Zhao, Zhengzheng Li, Jiaquan Chen, Guang Shi
Published 2015-09-29 by SAE International in United States
Trucks can carry heavy load and when applying the brakes during for example a mountain downhill or for an abrupt stop, the brake temperatures can rise significantly. Elevated temperatures in the drum brake region can reduce the braking efficiency or can even cause the brake system to fail, catch fire or even break.It therefore needs to be designed such to be able to transfer the heat out of its system by convection, conduction and/or radiation. All three heat transfer modes play an important role since the drum brakes of trucks are not much exposed to external airflow, a significant difference from disk brakes of passenger cars analyzed in previous studies. This makes it a complex heat transfer problem which is not easy to understand. Numerical methods provide insight by visualization of the different heat transfer modes.Presented is a numerical method that simulates the transient heat transfer of a truck drum brake system cooldown at constant driving speed. A 3D CFD Lattice Boltzmann based solver, which calculates the convection, is 2-way coupled to a radiation and…
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Validation Study for the Introduction of an Aerodynamic Development Process of Heavy Trucks

Exa Corporation-Bo Li, Heinz Friz
FAW R&D Center-Shaoyun Sun, Xinyu Wang, Qiang Fu, Kelong Lu, Zuofeng Pan
Published 2014-09-30 by SAE International in United States
A challenge for the aerodynamic optimization of trucks is the limited availability of wind tunnels for testing full scale trucks. FAW wants to introduce a development process which is mainly based on CFD simulation in combination with some limited amount of wind tunnel testing. While maturity of CFD simulation for truck aerodynamics has been demonstrated in recent years, a complete validation is still required before committing to a particular process. A 70% scale model is built for testing in the Shanghai Automotive Wind Tunnel Center (SAWTC). Drag and surface pressures are measured for providing a good basis for comparison to the simulation results. The simulations are performed for the truck in the open road driving condition as well as in an initial digital model of the aerodynamic wind tunnel of SAWTC. A full size truck is also simulated in the open road driving condition to understand the scaling effect. As a 70% scale model of a heavy truck is seen to be close to the limits of the SAWTC wind tunnel, an attempt is made…
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Aerodynamic Shape Optimization of an SUV in early Development Stage using a Response Surface Method

SAE International Journal of Passenger Cars - Mechanical Systems

Exa Corporation-Bo Li, Andrea Shestopalov, Paul Stewart, Heinz Friz
FAW R&D Center-Shaoyun Sun, Qiang Fu, Jing Zhao, Long Ma, Shijie Fan
  • Journal Article
  • 2014-01-2445
Published 2014-09-30 by SAE International in United States
In the development of an FAW SUV, one of the goals is to achieve a state of the art drag level. In order to achieve such an aggressive target, feedback from aerodynamics has to be included in the early stage of the design decision process. The aerodynamic performance evaluation and improvement is mostly based on CFD simulation in combination with some wind tunnel testing for verification of the simulation results. As a first step in this process, a fully detailed simulation model is built. The styling surface is combined with engine room and underbody detailed geometry from a similar size existing vehicle. From a detailed analysis of the flow field potential areas for improvement are identified and five design parameters for modifying overall shape features of the upper body are derived. In a second step, a response surface method involving design of experiments and adaptive sampling techniques are applied for characterizing the effects of the design changes. The characterization is followed by an optimization step to find the best possible drag improvement from these design…
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Optimization of the Underbody Layout of a Small Van for Better Aerodynamics Using Digital Simulation

Exa Corp.-Bo Li, Long Wu, Heinz Friz
SAIC-GM-Wuling Automobile Co., Ltd.-Wei Yang, Xuemao Zhou, Jing Peng
Published 2014-04-01 by SAE International in United States
The Wuling Rongguang is a small van which uses a mid-engine layout where the engine is located underneath the floor panel in-between front and rear wheels. A particular challenge for this kind of layout is the protection of the engine against soiling. Typical protective measures consist of large mudguards in combination with an engine cover. While needed for soiling protection, these parts can have a strongly adverse effect on aerodynamic drag.This paper describes process and the results of the aerodynamic optimization of the underbody of the Wuling Rongguang. Because design changes had to be evaluated for aerodynamics performance as well as for their effect on the soiling, a digital approach was used which allowed to do the soiling analysis as a post processing to the flow simulation. As a first step, a baseline model was built and analyzed. This included the development of a soiling model taking into account wheel spray and splashing effects. The soiling model used available best practices where available and was also calibrated against some road test results to ensure a…
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Aerodynamic Characterization of the Design Changes for the Facelift of the VW Bora

Exa Corp.-Bo Li, Amanda Learned, Rui Song, Heinz Friz
FAW-VW-Yan Jiang, Jingyan Liu, Qiming Chi, Fang Lu
Published 2014-04-01 by SAE International in United States
The recent facelift of the Chinese version of the VW Bora incorporated several changes of the styling of the upper body. In particular, front facia, A-Pillar and rear end were subject to design changes. As major effects on the aerodynamics performance were not expected, extensive wind tunnel testing for the upper body design changes was not included in the development plan except for final performance evaluation. Nevertheless, an aerodynamic study of the effects of the design changes was undertaken using a CFD based process. At the same time, the facelift offered the opportunity for reducing the aerodynamic drag by improving the underbody flow. The design of the engine undercover and the wheel spoilers were considered in this effort. For this purpose the CFD based aerodynamic study was extended to include respective design features. The whole study was carried out using a response surface method as a mathematical model to characterize and understand the effects of the design changes and their interactions. This approach allowed achieving best possible insight at a minimal effort. In addition, possible…
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Particle Number and Size Distribution from a Diesel Engine with Jatropha Biodiesel Fuel

Tongji University-Pi-qiang Tan, Zhi-yuan Hu, Di-ming Lou, Bo Li
Published 2009-11-02 by SAE International in United States
A biodiesel fuel, obtained from Jatropha seed in China, was tested in a direct injection, high pressure common-rail diesel engine for passenger cars. Effects of biodiesel on particle number and size distribution of the diesel engine are studied using an Engine Exhaust Particle Sizer (EEPS). Base petroleum diesel fuel, 10% and 20% v/v biodiesel blends with the base petroleum diesel fuel, the biodiesel fuel (B0, B10, B20 and B100 fuels) were tested without engine modification.For all test fuels, the particle number and size distribution show unimodal or bimodal log-normal distribution, with a nucleation mode peak value in 6.04nm to 10.8nm particle diameter, and with an accumulation mode peak value in 39.2nm to 60.4nm particle diameter.With the biodiesel blend ratios increasing, the number of nucleation mode particles increases and the particle size at peak value also gets larger, and the number of accumulation mode particles decreases and the particle size at peak value gets smaller, and the total particle number ascend at most engine operating conditions. Nucleation mode particles dominates the total particle number, and accumulation…
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