Research On Noise Control Optimization Of Engine Intake System Based On Finite Element Simulation

With the rapid development of China’s economy and the improvement of people’s living standards,automobiles have become the most important means of transportation in daily travel.The problem of automobile noise pollution is becoming more and more serious.Therefore,the relevant laws and regulations formulated by the state put forward increasingly stringent requirements for automobile noise control.The engine intake system is one of the main sources of noise pollution caused by automobiles powered by traditional engines,and the control measures are one of the main directions of automotive noise control at present.In this paper,the source and mechanism of noise in the intake system of automobiles,especially their engines,are studied.On this basis,the acoustic characteristics of mufflers commonly used in the intake system of engines are analyzed by using the method of duct acoustics.Taking a Helmholtz muffler as the research object,the transmission loss of the muffler element in the absence of flowing ideal air at room temperature and pressure is calculated by using three-dimensional acoustic frequency domain finite element method,and its principle and calculation process are described in detail.The simulation calculation process is solved by using the acoustic module in LMS Virtual.Lab.Similarly,taking the Helmholtz muffler as the research object,the transmission loss of ideal air without flow at ambient temperature and pressure is measured by using the two-load standing wave tube method of muffler.The simulation and experimental results are compared,and the results are basically in agreement.The accuracy of the acoustic finite e lement simulation method is verified by the two-load standing wave tube experiment,which provides a methodological guidance for the acoustic performance evaluation in the design process of the silencer.Taking the intake system of an automobile engine as the research object,the noise characteristics of the original engine nozzle and the noise control performance of the intake system are analyzed by means of vehicle noise measurement and three-dimensional finite element simulation,and the main noise frequ ency bands of the original engine which are not up to the standard and the inadequacy of the noise control capability of the original engine intake system are understood.Taking the high frequency HISS noise,low frequency resonance noise and order noise i n the nozzle noise of the original machine as the control object,based on the three-dimensional acoustic finite element method,the corresponding silencing elements such as air filter,braided pipe and Helmholtz muffler are designed,and their silencing p erformance is simulated by three-dimensional finite element method.Taking the four intake system muffling schemes composed of muffling elements as the test object,the noise situation of each scheme was obtained and analyzed through the vehicle noise experiment in the hub laboratory.All the schemes reached the target value of noise control of the nozzle,of which the scheme 04 was the best one,and the total sound pressure level was lower than the development target 4-10 dB as a whole.The results show that the noise control of the engine intake system is significantly effected by adding air filter,braided tube and Helmholtz muffler.The analysis and development method adopted in this paper is effective and reliable,and has certain engineering practical and reference value.