Pass-by Noise Prediction of a Vehicle 2019-32-0593
The forthcoming pass-by noise regulations have impacted the automotive sector, which further leads to the reduction of noise in the vehicle. The prediction of pass-by noise at an early stage will reduce the overall cost as well as time for an automobile industry and helps to reduce the overall product development life cycle. This supports the design activities of a vehicle.
Msc ACTRAN/NASTRAN/ADAMS and GT Suite are major tools used in the present study to develop a simulation method to mimic the predefined testing norms. In Actran interior and exterior noise propagation is performed. Interior noise flow obtained by compressible flow analysis which uses exhaust/intake line velocity/temperature as boundary condition. The exterior noise propagation obtained by direct frequency response using acoustic duct mode with unit pressure injected into the intake and exhaust system and compressible flow field map results as input, this will take care of both noise propagation. Similarly for engine exterior noise radiation done by Nastran unit frequency response analysis and later actual loads from multi-body dynamics multiplied with direct frequency response analysis in Actran.
Finally the python script is developed to find the acoustic transfer function between the unit pressure pulse in Actran/Unit frequency response in Nastran, also the actual intake/exhaust pressure pulse excitation from 1D GT suite model/Actual engine Multibody loads that all are simultaneously multiply one by one for each engine revolution result gives the overall sound pressure levels radiated noise (OSPL) of the motorcycle.
It is observed that the final pass-by noise simulation results the main contributions of exhaust system are in acceptable range.
RajaGopal B., Santosh Gannu, Abhilash M, GS Krishnamurthy, Rod Giles
CAE-NVH, Product Development, Royal Enfield, Chennai.
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