Multi-field Analysis And Optimization Of Vehicle Exhaust Muffler

With the increase of vehicle ownership in China,the issue of vehicle noise pollution is becoming more and more serious.Engine noise is one of the main noise sources of vehicle,as the main part of engine noise,the exhaust noise is an important factor that affect comfortableness.Thus,how to design exhaust muffler with high noise elimination and low pressure loss is a major project of the engineer.Based on the research of typical muffler unit pressure loss and transmission loss,bench testing,flow and acoustic field simulation are carried out for a type of diesel engine exhaust muffler,the improvement and optimization program is proposed,the multi-field performance of optimization program is analyzed by simulation method.The main points of this paper are summarized as follows:(1)First,reviewed the theory and performance evaluation of exhaust muffler,and then on the basis of flow field theory,the pressure loss of expansion chamber,intubation and straight-through perforated tube are analyzed by Fluent,the relationship between pressure loss and structural parameters such as expansion ratio,length of intubation,perforation and aperture is studied,finally a new pressure loss correction formula is put forward based on the results of fluid simulation,the results provides reference to the exhaust muffler aerodynamic performance analysis and prediction.(2)Based on acoustics finite element method,the influence of muffler unit structural parameters on transmission loss is studied.For a type of exhaust muffler,the insertion loss,power loss ratio and spectrum characteristics are obtained,the performance of pressure field,temperature field,velocity field and acoustic field are simulated,the direction of muffler optimization is determined.(3)Based on the results of the muffler pressure loss and transmission loss,consider the space for the muffler at the same time,the acoustic and aerodynamic performance is optimized,the multi-field performance of the optimized muffler is analyzed,the simulation results of the before and after improvement are compared,result shows that the proposed optimization program can achieve the purpose of multi-field optimization.In summary,for the practical engineering problem,the research of muffler multi-field performance and experiment,combined with the results of simulation analysis and experimental analysis have a theoretical reference and can be used in the practical engineering applications.