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At SAIC-GM-Wuling (SGMW) the greenhouse wind noise performance of their vehicles has gained a lot of attention in the development process. In order to evaluate and improve the noise quality of a newly developed SUV a digital simulation based process has been employed during the early stage of the design. CFD simulation was used for obtaining the flow induced exterior noise sources. Performance metrics for the quality were based on interior noise levels which were calculated from the exterior sources using a SEA approach for the noise transmission through the glass panels and propagation to the driver’s or passenger’s head space. Detailed analysis of the CFD results allowed to identify noise sources and related flow structures. Based on this analysis, design modifications were then applied and tested in a sequential iterative process. As a result an improvement of more than 2 dB in overall sound pressure level could be achieved.

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.

Automotive manufacturers are under continuous pressure to satisfy changing consumer demands and regulatory requirements in an increasingly competitive landscape. This requires Aerodynamic departments to evaluate more design ideas in less development time. Aerodynamic departments are seeking to speed up their analysis in order to provide more feedback on performance to design and styling. Vehicle designers already leverage Computational Fluid Dynamics in order to quickly assess vehicle aerodynamic performance during product development. However, in order to meet modern development challenges, reducing simulation cost and turn-around-time is necessary. To that end, a novel approach to reducing simulation time of vehicle aerodynamics without sacrificing accuracy was tested in this paper. The methodology is called Transient Boundary Seeding, and enables the usage of a reduced simulation domain without the loss of information from the omitted region.