Numerical Simulation On Aeroacoustics Of Vehicle’s External Surface

As the engine noise, exhaust noise, transmission noise and tyre noise being bettercontrolled, and vehicle speed being enhanced, aeroacoustics of high speed vehiclewhich attracts people more and more attention, has become one of main noise sources.Computer, CFD technology and Computational Aero Acoustics (CAA) which belongsto new interdisciplinary being developed rapidly in nearly10years provide a newway to the research of vehicle aerodynamic noise. Computational Aero Acousticsadopts numerical analysis method. It solves the corresponding mathematical equationsand it researches near field, far field and characteristics of inside aerodynamic noiseof vehicle by computer to provide the scientific basis for vehicle design.The wind noise part of the interior vehicle noise roots in pressure fluctuation ofouter part of the vehicle. The turbulent boundary layer existed on vehicle surface willcause pressure fluctuation to the external surface when driving. With Roewe350model established by CFD software Fluent, considering the correlative keys, such asmesh size, turbulence model etc., the external surface pressure fluctuation wasresearched. The result shows that the offset on top of windshield, outside mirrorbracket, door handle are the main parts causing aeroacoutic, where the flow separationis a little strong.Based on completed analysis result, to modify the configuration of the parts andresearch the pressure fluctuation on side window by CFD method, the sound pressurelevel and surface flow separation has a good improvement.Aeroacoutic wind tunnel test is carried out to validate whether the numericalsimulation is correct or not. This test is done at Shanghai Automotive Wind TunnelCenter. The sound pressure level on driver’s ear is measured during test to comparewith the conclusion done by numerical simulation, the consistent results mean thatnumerical simulation method is capable for aeroacoutic research.