Research On Performance And Optimization Of Vehicle Exhaust Muffler

With the maturation and integration of acoustic software and CFD software on the market,whether numerical simulation of muffler can provide more and more accurate reference for actual design and optimization,and how to reduce development costs and cycle issues is the focus of research about muffler in the future.Combining with an optimization project of a three-cylinder engine,this article used different software to simulate the acoustic performance and aerodynamic performance of the exhaust muffler and proposed optimization schemes.The main work contents and innovations of this article are as follows:Using the one-dimensional volume element software GT-Power and the FEM module of software Virtual.Lab to simulate and analyze the acoustic performance of the muffler.Comparing the transmission loss test results to evaluate the simulation accuracy of the two acoustic software: the simulation results of Virtual.Lab software were close to the experimental value on the entire frequency band and had better the simulation accuracy,more accurately reflection on the acoustic performance of the muffler.However,GT-Power software simulation results were close to the experimental values just on the low frequency range and could not capture peaks of the transmission loss curves on the mid-high frequency band,the trends were consistent with the experimental values.Comparing the two kinds of software from the point of development cost and cycle,GT-Power software had higher simulation efficiency and certain practical value and reference significance in the early period of muffler design and development.Using FLUENT software to simulate the flow fields of the exhaust mufflers,and make a research on the internal distribution of pressure,air flow velocity,and turbulent kinetic energy.The pressure loss curves of the muffler were drawn by setting different velocity on FLUENT and airflow mass flow rate on the pressure loss calculation platform established by GT-Power respectively.Evaluating the accuracy of those two simulation software by the pressure loss test data: the simulation results of the pressure loss curve of were both close to the experimental value,and the simulation accuracy was credible.The GT-Power software was easy to establish models and calculated pressure loss more faster.The calculation process of FLUENT software was more complicated,but it could clearly show the details of pressure,flow velocity,and turbulent kinetic energy of the internal flow field of the muffler,which was beneficial to the later optimization.Based on the above performance analysis,optimization solutions for front and rear mufflers designed with parameters such as Helmholtz resonator,reflow structure,and impedance compound structure was proposed,and tailpipe noise simulation for each solution was performed by GT-Power software and verified in the semi-anechoic chamber of the vehicle.The comparison results showed that the simulation results of GT-Power software were consistent with the test results.The simulation results could distinguish the advantages and disadvantages of the improved solutions,greatly shortened the design cycle and reduced the development cost,having reference value.Combined with the test results of the backpressure test,some optimized solutions achieved the expected improvement goals.