Application Of SEA In Aerodynamic Noise Research On The Vehicle Exterior Flow Field

With the development of our automobile industry and standard of living of our country, the requirement on comfort and safety of automobile is raising. Then, the noise and vibration in cab are becoming highly important questions. So for improving the comfort, it has an all-important meaning to reduce the noise and vibration in automobileUnder the drastic competition of the auto market, automobile designers should forecast and analyze the noise and vibration of car at the early of full vehicle design. This can avoid repairing the problems of noise and vibration at the end of the design, because a lot of new design can make huge waste of manpower and material resources. Now, using statistical energy analysis (SEA) can compute and analyze high frequency noise and vibration in cab, so the designer can make a close analysis of response of noise in vehicle, then optimize the design of this problem.In this paper, on the basis of science and technology development key project of Jilin Province—"analysis and control of wind noise and roar noise in saloon car", research on our country's saloon car. On the basis of reading domestic and overseas references about aerodynamic noise for the vehicle in the exterior flow, sum up and narrate those. And combining statistical energy analysis and simulate analysis software-AutoSEA, this paper make a simulate analysis computer on the car made in our country.First, in AutoSEA build three-dimension entity modeling of the car. Then according to the requirement of SEA, rationally carve up the structure and cavity subsystems of the car. At last, according to the parameters offered by the company, enact the parameters ofsubsystems in the software.There are three highly important analysis parameters in SEA: modal density, coupling loss factor (CLF) and damping loss factor (DLF). These parameters can be assured by theory compute and experimentation. In car SEA model, modal density of systems is assured by theory compute. In car SEA model, CLF of construct systems is assured by theory compute, and CLF of sound cavity systems is assured by experimentation. In car SEA model, DLF of systems is assured by SEA software.The excitation which input the car are assured by a simulate experiment of wind tunnel test. In GAMBIT which is the CFD front manage software, build the car geometry modeling and plot the griddling of the wind tunnel test and the car which is in it. At last, transmit the modeling to Fluent and compute. The result of the simulate experiment of wind tunnel test can be used as the excitation which affect on the subsystems.With the statistical energy analysis model, analyze the wind noise in vehicle and computer the average A sound level of front-up sound cavity, and then compare it with test result. This way can check up the validity of the model, and forecast noise.With the valid statistical energy analysis model, analyze the effect of the modification of vehicle body decorations and increasing the thickness of the vehicle body glasses. The result shows that it can control wind noise in vehicle through the modification of vehicle decorations and increasing the thickness of the vehicle body glasses.