Study On Noise Control Of Turbo-charged Engine Intake System

In order to improve the power and fuel economy of automotive engines and improve their emission characteristics,booster technology is widely used in automotive engines.Turbocharged engine has become one of the basic models of automotive engines.However,the use of turbochargers makes the car's noise problems more prominent,and these noise problems are mainly existed in the intake system including the compressor.With the increasing demand of modern society for NVH(Noise,Vibration,Harshness)performance including noise,the research on noise generation and control of turbocharged intake system is necessary and of great significance.Compressors are the functional elements and main noise sources of turbocharged intake systems.In this paper,the compressor model is firstly established to simulate the internal flow field characteristics of the compressor,and the speed and pressure distribution of the air flow in the impeller region,the vaneless diffuser and the volute region are analyzed.Based on the steady flow field,the broadband noise source model method is used to calculate the acoustic power distribution.The analysis results show that the impeller area is the main noise source of the compressor and the blade leading edge of the impeller inlet and the blade tip near the compressor housing have the highest sound power level.Then,on the basis of the unsteady flow field,acoustical analogy method was used to simulate and calculate the noise spectrum characteristics of different places inside the compressor.Based on the compressor model,the pressure relief flow model including a pressure relief valve and a pressure relief tube is established.The flow field and the sound field are numerically calculated,and the noise generation mechanism and main noise sources in the pressure relief condition are analyzed.Then the pressure relief flow model is optimized to control the pressure relief noise from the noise generation angle.The analysis results show that the compressor impeller and the pressure relief valve are the main noise sources for the noise of the pressure relief condition.By changing the pressure tube's access position from the low pressure tube to the compressor's inlet distance,the airflow noise in the impeller area during the pressure relief condition can be reduced.According to the simulation results,the pressure relief system of an automobile with obvious pressure relief noise was rebuilt,and the interior noise in the pressure relief condition of the vehicle before and after reformation was compared and the interior noise of the vehicle was greatly improved.For a certain turbocharged intake system noise engineering problems,noise control from is performed from the propagation route.After testing the problematic noise,by analyzing the objective data combined with the subjective evaluation method,according to the optimization goal,the critical frequency band of the problem noise is determined.Check the main transmission path of noise and diagnose the location of noise radiation in each key frequency band.Noise reduction measures were proposed for the problems.Finally,the actual vehicle test verified that the noise control effect of the above scheme is worked and the target value was achieved.