Systematical Study On Acoustics Prediction And Abnormal Noise Control Of Internal Combustion Engine Intake System

The intake system noise of internal combustion engine(ICE)not only determines the speedup pass-by noise level of the vehicle,but also influences the interior noise and the riding comfort in the car,which leads an important and significant topic of controlling and attenuating the intake noise at present.In this paper,the advanced techniques of digital simulation and experimental analysis were carried out to thoroughly explore the intake acoustic performance,the aerodynamic noise,and the turbocharger radiated noise,et al.In result,some remarkable achievements were acquired as following:The AFEM approach to predict the transmission loss was propposed specificly aiming at mutitiple inlet and single outlet silencer.The results show great agreement with the theoretical data.Therefore,the mentioned approach was applied in analyzing the acoustic performance of intake manifold,which took the lead at home.Considering the research and development of the air intake manifold,the numerical simulation methods were adopted to analyze the fluid characteristics.Typically,the simulation results were validated through steady-flow bench test data.Moreover,the structural optimization was specificly made to meet the engineering demond under actual working codition.The experimental and numerical methods,including the AFEM and CFD approaches,were adopted to analyze the acoustic performance of the air cleaner and the filter element.In addition,the entire intake system of a certain naturally aspirated engine including the manifold was modeled,and the acoustic performance was investigated typically on the acoustical influence or contribution of the manifold.In conclusion,the numerical simulation approaches proves to be effective in analyzing the ICE intake system,and the research in this work would provide the theoretical basis and technical guidance for engineering application.The CFD model and the acoustical finite element model of the intake system were established,and the simulation results based on such models were consistent with the bench test data.Thereafter,the LES-AFEM coupled numerical simulation approach was carried out to predict the aerodynamic noise inside the intake system.Then,by combining the bench test with the simulation solution,the structural parameters of the porous materials were acquired accurate enough to simulate the flow and acoustic properties of the filter element inside the air cleaner.Finally,the aeroacoustic characteristics of the whole intake system including filter element were analyzed,and the acoustical influence of the filter element was investigated combined with the local airflow as well.The 3D time-domain pulse approach was utilized in acoustic design and analysis of ICE intake system.The NVH issue of the vehicle turbocharger system was systematically investigated through the road test for several test cars.Accordingly,the high-frequency muffler and the broadband muffler protypes were designed and manufactured in order to minimize the turbocharger squeak noise and the snuffling noise respectively.In general,the developed system attenuates the intake noise remarkably,as well as improving the interior sound quality.