Structure Analysis Of Automobile Exhaust Muffler Based On Acoustic-Fluid-Thermal Multi-Physical Coupling

Exhaust muffler is an important component of automobile,which has a key influence on the dynamic performance,economic performance and emission performance of automobile.Its performance quality directly determines the exhaust loss of the engine and the emission of pollutants and the size of aerodynamic noise,which will also have an impact on the working efficiency and service life of the engine.In order to respond to the national call for energy conservation and emission reduction this major work program,improve and optimize the automobile exhaust muffler,noise,back pressure and pollution to minimize,is now the primary task of automobile design.Therefore,it is of great practical significance to analyze the acoustic and aerodynamic performance of the exhaust muffler.The muffler studied in this paper is an automobile exhaust muffler.Its design is based on the standard automobile muffler model,which utilizes two kinds of muffler mechanisms: the expanded muffler of the cavity,and the sound wave generated by the heat loss of the flow impedance in the micro-perforated plate.The main work of this paper is as follows:In this paper,COMSOL software is used to simulate the influence of airflow on the acoustic performance of automobile exhaust muffler.Firstly,the acoustic and fluid coupling simulation method is verified by the helmholtz resonance chamber experiment,and then the physical model of automobile exhaust muffler is created.The results show that the noise attenuation performance of the muffler is worse in some frequency bands and better in some frequency bands,especially in the frequency peak of the transmission loss and even the peak deviation.The simulation analysis of different structural parameters of exhaust muffler based on the method of acoustic fluid coupling shows that the number of expansion chamber,the size of expansion chamber,the diameter and length of internal intubation all have a certain degree of influence on the background flow field inside the muffler,and then affect the muffler’s muffler’s silencing ability.The exhaust gas from automobile engines is a high-temperature airflow,and the temperature has a great influence on the gas properties.The increase of temperature will lead to the decrease of the gas density and the increase of the gas viscosity coefficient,thus affecting the properties of the background flow field inside the muffler.In this paper,the coupling calculation and analysis of acoustic flow and thermal field are realized by using 3D simulation method.The results show that the temperature affects the performance of muffler through the action of flow field and sound field.Same simulation method based on acoustic streaming thermal coupling simulation analysis was carried out on the exhaust muffler of different structural parameters,the results showed that in only considering the influence of the structure on the muffler performance rule,temperature has little effect on flow field velocity,can be ignored,but have a great change of temperature on the acoustic performance of muffler,so want to focus on the silencer acoustic performance,temperature is one of the factors must be considered.In this paper,based on the calculation method of physical field coupling simulation analysis was carried out on the exhaust muffler,and analyze the performance under different structure parameters of muffler.The exhaust muffler to evaluate flow field and acoustic field,which can greatly shorten the design cycle of the exhaust muffler,provides methods and technical reference,and save the cost of research and development.