Research On The Influence Of Structural Elements On The Aerodynamic Performance And Acoustic Performance Of Muffler

With the development of science and technology,people have higher and higher requirements for automotive NVH performance.As the main device to control the exhaust noise of automobile engines,the muffler with excellent acoustic performance and good aerodynamic performance has always been the unremitting pursuit of people.The length and diameter of the basic structural unit(Acoustic unit with inlet pipe and outlet pipe inserted into the expansion cavity,etc.)directly determine the aerodynamic and acoustic performance of the muffler.In order to obtain the better overall performance of the muffler,this topic uses numerical simulation methods to explore the influence of multiple structural elements on the aerodynamic performance(pressure loss)and acoustic performance(transmission loss)of the muffler.This topic takes a certain type of automobile engine muffler as the research object,and the internal air flow path and acoustic units are analyzed.Based on the plane wave theory and semi empirical formula,the influence of acoustic length and diameter of intake pipe and outlet pipe inserted into the expansion chamber on the muffler’s noise elimination performance and aerodynamic performance is studied by using the simulation software GT-power,in order to explore the influence of the single structural element on the performance of other structural elements on the muffler.It turns out that(1)When the equivalent pressure loss is obtained by changing the length of the inlet and outlet pipes inserted into the expansion cavity(La,Lb),there is a certain difference in the transmission loss,and the range of change becomes larger as the equivalent pressure loss decreases;While the equivalent average transfer loss is obtained,the variation range of pressure loss increases with the decrease of the equivalent average transfer loss.(2)When the equivalent pressure loss is obtained by changing the inlet pipe and the diameter inserted into the expansion cavity of the inlet pipe(Da,Db),the transmission loss also has a certain difference,and increases with the increase of the equivalent pressure loss;While the equivalent average transmission loss is obtained,the pressure loss variation range decreases as the equivalent average transmission loss increases.Finally,the evaluation system considering acoustic performance and aerodynamic performance is established to evaluate the structural elements.At the same time,a combination area of structural parameters that has better performance than the original muffler based on boundary condition is found which is a comprehensive consideration of acoustics for exploration,and the change of modal frequency of muffler structure before and after optimization is compared.This project provides a new idea for exploring the better muffler performance considering acoustics and aerodynamics,which is of great significance in engineering practice.