Research On Interior Aerodynamic Noise Resulted From Styling Basic Profile Of Car Rearview Mirror

The level of vehicle noise is one of the main factors affecting the level of comfort. With speedof a motor vehicle improves continuously, aerodynamic noise has been the major noise sourcewhen a car is running at a high speed. It has been one important research topic to control thelevel of aerodynamic noise nowadays. As a bulged part of car exterior, the outline of a rearviewmirror makes a difference on aerodynamic noise of a car directly. In recent years, the studies onthe rear mirror aerodynamic noise are on the rise, while our country is still short of systematicand thorough studies in this domain. Given the above, this paper took out the factor of raisingposition of a rearview mirror as research contents to establish three representative rearviewmirror models for the interior noise analysis.In order to save simulation time, this paper chooses the half body model for numericalsimulation analysis, and to determine the size of the computational domain according to the sizeof the car body model. Triangular grids are generated on body surface and the boundary of thecomputational domain, and using tetrahedral grid to simulate fluid. Outflow field simulation isdivided into steady and transient two processes, choosing k-ε turbulence model for steady-statesimulation. This paper analyzes the flow field characteristics and pressure distribution obtainedin the steady-state simulation to get a preliminary understanding about car exterior aerodynamicnoise. First used large-eddy simulation model for transient stable process, and get the value oftransient simulation after importing the monitor information. After external flow fieldsimulation is complete, this paper deeply analyses the spectral data of the monitoring points, andexplain the cause of the difference. The comparative analysis of aerodynamic noise data on thesame area of different model provide a strong data support for the validity and consistency of themodel simulation.In this paper, CFD-SEA coupled method is selected to simulate the interior noise. Therefore, statistical energy analysis model is firstly established through the steps of SEA subsystemdivided—definition of subsystems connected relationship—determination of material anddimension—setting of key parameter. Then load the result obtained in exterior flow fieldsimulation process to SEA model, through computation, aerodynamic noise level of the driver’shead tune on three different rear-view model are obtained.Comparing and analyzing the discussed simulation results, the phenomenon that differentrearview mirror models (up—raised, middle—raised, down—raised) effect the level ofaerodynamic interior noise obviously especially when the frequency is in the range of100to5000Hz. The up—raised one is more effective compared with the other two and it made soundpressure level reduce about1dB. This paper analyzed the difference in theory and explained thecause of this phenomenon at the same time. So it can provide a theoretical basis fornoise-decreasing device of a rearview mirror.