Performance Analysis Of Muffler In Vehicle Exhaust System

The design of the exhaust system is directly related to the vehicle dynamics, comfortand economy. With the increasingly strictness of vehicle noise，the design of the exhaustsystem is getting more and more people’s attention. That makes the optimal design of theexhaust system be one of the key automotive designs and it has important practicalsignificance. At the present stage, the design of the exhaust system is still in the stage ofpassive noise reduction, and there are some limitations. This paper combined withpassive and active control methods through computer simulation technology, andanalyzed and studied the transmission loss and the pressure loss of the exhaust system.This paper has established the numerical models of the front and rear mufflers basedon a certain type of exhaust system from a passenger vehicle. Respectively, used VirtualLab Acoustics for analysis of acoustic performance and used Fluent for analysis of fluidcharacterization. Got the transmission loss and pressure loss of the front and rear mufflers.Analysis of sound pressure distribution, velocity and pressure distribution in the flowfield of each muffler were commented in detail and some unreasonable structures werepointed out. Tested the effect of the muffler on exhaust system of the vehicle, themeasurement results and simulation results were similar which verified the correctness ofthe simulation method. In addition to this, the influences of the temperature, flow andother environmental factors on acoustic performance of the muffler were analyzed.According to the basic anechoic principles and the analysis of the muffler, fourimprovements have been designed on the front muffler and two improvements have beendesigned on the rear muffler. After adjusted each data of the improvements and comparedthe simulations of the transmission loss before and after the improvements, finally got thebest improvement program. Besides that, the transmission loss of the exhaust systemwhich equipped with front and rear mufflers has been also analyzed, that providedguidance for the practical engineering design.A model of active noise control of engine exhaust system based on Filtered-XLMS algorithm has been established by the use of Matlab. The effect on the system of thelength of filter and the convergence parameters was studied in detail. And the model wasapplied on various rotating speed. The result of the simulation indicated that the designedalgorithm speeded up the convergence, possessed strong robustness and made the steadystate error smaller. In addition to this, the designed algorithm provided theoretical supportfor further practically realizing the active noise control of the engine exhaust system.