Study On Automobile Intake Resonatory Muffler Based On Three-Dimensional/One-Dimensional Models Coupling Technology

With the car industry developing rapidly, the intake noise of car's engine has become one of major noise sources on the impact automobiles noise. Environmental pollution problems brought by more and more traffic vehicles have become a large hazards affecting residents living,threatening to public health. At present,the study about exhaust noise control for more,else,the intake noise not enough,the intake noise has become the focus of noise control. Thus,studying into the intake noise reduction system deeply has become a burning question.According to the characteristic of the larger intake noise for Chang-an Jiexun JL486Q1type car,that applying to three-dimensional/one-dimensional coupling technology and designing reasonable intake muffler may supply the reference for the design and improvement to the muffler in the future. At the same time,It may predict performance and transmission loss of the muffler at the product design stage,inspect the influence to dynamics and economy of engine after the resonator installation,it can greatly shorten the product development cycle and reduce the product cost.This paper bases on the mesh generation software GAMBIT,engine simulation software GT-POWER,professional acoustic software SYSNOISE and fluid dynamics software FLUENT as platform,through comprehensively using finite element method,boundary element method,finite volume method and so on,to simulate and analyze the acoustic performance for the basic noise reduction unit and flow field.on the basis of analyzing about the mechanism by intake noise generating and Helmholts noise reduction principle, applying to acoustic finite element method to analyze different structure parameters,which include the shape,volume, throat size,mian tube of the resonator on the influence of the muffler performance, concluding the mathematical expressions for resonant frequency;Applying to the softwares for GT-POWER,FLUENT,combined with finite volume method,according to the related parameters of the gasoline engine for JL486Q1type,the engine model together with the joint model of the engine and the intake resonator is established,and describing the muffler flow field distribution under the condition of engine working,analyzing the changing circumstances to the engine power,engine economy,air inflow and air intake efficiency after the resonator installation.Based on the finite element and boundary element (BEM/FEM)theory,using GAMBIT,NASTRAN for FLUENT and SYSNOISE software to establish the sound-solid coupling model for (?)esonator,studying the surface displacement response for the resonator and the change for (?)ound field radiation,analyzing the influence on the acoustic field because of the change factors of the resonator shell thickness and structure damping (material);with the application of the research results,using the plastic molding technology,processing the intake resonator of chang- an Jiexun car,and doing the experimental research for the designed muffler. The engine performance test,the vehicle chassis dynamometer noise experiments and road noise experiment had been done.Simulation analysis and experimental results show that the resonant structure parameters have a direct effect on its resonant frequency.Resonant cavity peak for noise reduction mainly concentrates within400Hz in the low frequency region,the resonant cavity increases in volume,the noise reduction peak moves to the lower frequency,if the volume is the sameness,the resonant frequency, which has nothing to do with the change for the height and area of the cavity,is not changed. Noise reduction amount of resonant cavity is not enlarged as the volume increases, which is no rule.As the throat diameter and its length varies,the resonant frequency is different, and the greater the diameter, the greater the resonant frequency,the greater the length,the resonant frequency moves to the lower frequency; Engine intake noise mainly focuses on the three frequency points,138Hz,276Hz,and366Hz.The intake noise of which has different degree in the fall after the muffler installation, the largest decline for7.5dB(A),the experiment of acceleration driving indicates that the vehicle noise outside declines from89.1dB(A) to83.6dB(A), the largest decline for5.5dB(A),which lays the foundation for the noise reduction in next step. Engine power, fuel consumption,air inflow and air intake efficiency do not change obviously compared with the original car,the mean error is less than5%.This illustrats that the model can predict the performance index of muffler and engine well.In this paper,through theoretical analysis and experimental verification,the relationship characteristic between the volume ratio for the cavity with neck tube and noise reduction amount,the resonant frequency, the conversion relationship between the resonant frequency and the resonator volume, main tube diameter and the noise reduction, and so on,have been put forward creatively;The frequency range for the greatest noise has been found;Using the engine, CFD and acoustic softwares, as well as three-dimensional/one-dimensional coupling technology,the coupling and matching problem among the flow field,the acoustic field and the resonator have been solved.