Noise Test And Simulation Analysis Of Automobile Intake System Under Transient Condition

The noise of intake system has great influence on the performance of NVH(Noise,Vibration and Harshness),so the control of sound pressure level and sound quality of intake system noise has been widely concerned by researchers.In this thesis,the noise of intake system is tested and simulated,the relationship between the structure parameters and intake noise under transient condition is studied.Through designing reasonable structures,the intake noise pressure level is controlled below the target level.Meanwhile,from the auditory sensation of human ear,the intake noise can satisfy the subjective requirements of the driver.The four-load method and one-dimensional finite volume method are used to extract the sound source of engine intake noise respectively,and based on the experimental results,the accuracy of the two methods is discussed.It is found that in 0Hz-500 Hz,the intake noise source extracted by one-dimensional finite volume method is more accurate,while in 500Hz-1000 Hz,the four-load method has higher accuracy of sound source extraction.In this paper,the influence of the structure factor of the intake system on the performance of noise reduction is studied.Air intake system insert loss model and the air inlet noise analysis model is established,and by orthogonal analysis method,the influence of the muffler structure factor and the pipe structure factor on the total sound pressure level and order of the intake noise is studied.The results show that in the structure factor of the muffler unit the expansion ratio of the air filter has the highest sensitivity to the total sound pressure,and the diameter of the resonator connection tube has the most significant influence on the order noise.In the pipe structure factor,the total sound pressure sensitivity is most affected by the pipe diameter.In this paper,the intake noise under transient condition of the intake system is tested.By setting the sound insulation material in the outer wall of the hub and the engine room,the measurement accuracy of the air inlet noise is improved.The influence of the intake noise on the measurement results is compared,and the muffling effect of each part of the intake system is studied,and the influence of the acoustic mode of the air pipe on the intake noise is analyzed.Finally,the noise source of the intake system is analyzed.Finally,combined with the results of the previous chapters,the optimal design of sound quality for a passenger car intake system is carried out.The 2,4 and 6 order noise is regulated by designing the new intake system structure.Through the simulation analysis,experimental test and subjective evaluation,it is verified that the improved intake system structure can make the car reach the sense of motion sound quality.The transient noise test method and simulation analysis method proposed in this paper are of guiding significance to the comprehensive analysis process of the acoustic characteristics of the intake system.