The Acoustic Performance Design Of Passenger Vehicle Exhaust System Based GT-SUITE

This paper first introduces the impact of the new energy market and emission regulations of the traditional internal combustion engine,at the same time,people on the noise level of demand is increasing,the traditional internal combustion engine must improve noise performance at low speed in internal combustion engine is the main source of vehicle noise,and exhaust noise is a key breakthrough.The method of frequency domain and time domain for acoustic performance analysis of exhaust system is summarized,and the development history,advantages and disadvantages of these methods in exhaust acoustic performance research are introduced.Volatility is essentially a phenomenon of flow,and it is back to the theory of hydrodynamics.Considering the fact that pz small,considering the flow process of exhaust system is one dimensional state,we also introduce the discrete numerical simulation method of fluid dynamics: finite volume method.In order to analyze the acoustic signal,the signal theory is introduced.The noise source of exhaust system is expounded from the origin and generation mechanism of the noise source of exhaust system,and the main factors affecting the source of exhaust noise are also introduced.At the same time,the acoustic performance indexes of the exhaust system are also introduced.Finally introduces the common type muffler element: expansion muffler,a bypass type resonance muffler and muffler,and the calculation formula of transmission loss is presented based on the theory of plane wave.Through the analysis of expansion type resistant muffler with broadband noise attenuation characteristics of low frequency transmission loss,Pang resonant muffler has characteristics of low frequency narrowband noise,muffler on the larger acoustic attenuation ability in practice are often constructed impedance compound muffler to achieve silencing ability is low,medium and high frequency segment.The calculation of transmission loss,insertion loss,exhaust pressure loss and tail pipe noise in the exhaust system is calculated in GT-SUITE.Meanwhile,in GT-SUITE,the coupling calculation model of internal combustion engine and exhaust system is built based on actual parameters,and it is compared with the external characteristics of internal combustion engine under the test condition and the simulation platform.The design process of acoustic performance of exhaust system is introduced,which is mainly divided into three stages: acoustic target formulation of exhaust system,prediction and verification of acoustic performance of exhaust system.The acoustic target of the exhaust system is set up to decompose the noise reduction of the acoustic performance of the exhaust system according to the level of the acoustic target and the source of the internal combustion engine noise.According to the acoustic acoustic performance of exhaust system,determine the constraints and meet the chassis insertion loss of exhaust muffler and the external pipe in the system package volume and sectional form,design of the internal structure of the muffler,the preliminary scheme,the preliminary design scheme based on GT-SUITE performance analysis,to meet the requirements of the program and then lock for prototype production,and in the test of the performance of the vehicle or engine bench.If the requirements are not met,the optimization design is carried out.Finally,the flow field is illustrated by an acoustic design case of the exhaust system of a passenger vehicle.