Control Of Automobile Sunroof Noise And CFD Simulation

In recent years, as exhaust, engine, tire, drive trains, and other automobilenoise are reduced, aerodynamic noise on ground vehicle cruise condition isbecoming relatively more important, begun to attract widespread attention. Thisstudy would mainly analysis how to control the aerodynamic noise of sunroof.Firstly the numerical model of car body is established and the flow fieldcalculation domain size of car body is determined, then a numerical simulation onsunroof flow field is made, and three-dimensional grid on body surface is generatedwhich was suggested to meet the requirements, grid in key area (near sunroof) isfurther meshed so that the simulation could be more actual. Flow field simulationprocess is divided into steady-state simulation and transient simulation. In thesteady-state simulation, segregated solver,2nd Order SIMPLE,2nd Order Upwindand RNG k model are used for analyzing pressure distribution and flow fieldcharacteristics on sunroof, which would be provided reference for the interior noiseanalysis. The Large eddy simulation the grid model of WALE are selected intransient simulation, meanwhile, the iteration2order time progression would bespeed up the calculation process. For scientific precision, the central finitedifference model of better convergence and grid adaptive in space would also beused. And relevant parameter such as the time step is determined by the eddycurrent cycle near sunroof, to ensure that there are more sampling points in an offcycle of the eddy current, as to fully capture the sunroof wind vibration frequency.In the simulation analysis, the first, numerical simulation has been worked onautomobile surface exterior flow field at first, and then the sunroof wind buffetingnoise was studied on the basis. At last, the car model buffeting frequency and thesound pressure monitoring points were obtained. In this thesis, three kind of waysto control sunroof noise was studied, which are opening sunroof scientifically,install cavity in the sunroof’s forefront and changing the location of the sunroof inthe roof. The results of simulation show that these measurements can effectivelyreduce the aero-acoustics of sunroof, improve the interior noise environment.