The Acoustic Characteristics Analysis And Optimization Of The Integrated Muffler

The research of this paper is based on DFAC C66-474 models development project,the project aims to develop SWB models in accordance of C66-474 basic model,which is to reduce wheelbase from 3800 mm to 3300 mm and to shorten the overall fitting length from 1534 mm to maximum 1000 mm in terms of catalytic domain and muffler,at the same time to meet the requirement of performance objectives raised by engine unit.Therefore,the project team proposed to develop integrated catalytic muffers instead of split catalytic muffers so as to achieve performance objectives.The paper is to conducting CFD simulating calculation of internal flow fields of two alternative catalytic muffers with different internal structures by utilizing CATIA for establishing the model and ICEM to simplify modeling and meshing for F.E modeling establishment as well as to select and solve the modeling,setting air medium and define constraint condition via FLUENT,discusses the pressure loss of two structure kinds of catalytic muffler under different conditions,and make samples and catalytic muffler exhaust back pressure,measure two structure kinds of catalytic muffler exhaust back pressure.Then,the three-dimensional simulation of the catalytic mufflers of these two structures is carried out by using MSC.ACTRAN software,and the acoustic transmission loss analysis is carried out.Study on the effect of air velocity on the acoustic performance of the muffler,and studies the acoustic effect of catalytic carrier to integrated catalytic muffler,through the production of prototype and application of double load method in the laboratory measurement of free flow and flow samples under the condition of catalytic muffler transmission loss.By compared analysis of experimental data and simulation data to verify the correctness of the simulation results.At the same time,we optimized the structure of the integrated muffler.The simulation and experimental results show that the performance of the muffler is worse than that of the optimization.This provides theoretical basis and experimental method and improved design of positive catalytic muffler for the follow-up of more complex structure.