Study On Acoustic Performance And CFD Characteristics Of Catalytic Converter Muffler

Air pollution is becoming increasingly serious, fog and haze appears frequently, which sharpens people's concern about air condition. Motor vehicle exhaust pollution is one of the important causes of air pollution, more stringent emission standards for vehicles "state six" standard is also about to be implemented. It not only enhances the purification function of the exhaust system, but also improves the noise elimination function, and is more favorable for saving the space of the chassis to add catalytic conversion to muffler. Therefore, it is very necessary to carry out a thorough study of the purification muffler, the muffler performance and flow characteristics of the purification muffler are studied in this paper.The transfer matrix of catalytic conversion carrier is derived based on the one-dimensional plane wave theory. Then the transfer matrix method and finite element method are used to calculate the transmission loss of a catalytic converter in the literature and the experimental data were compared with the experimental data in order to verify the accuracy of the mathematical model of the catalytic conversion carrier. And then the different length, different perforation ratio and different flow resistance and different position of catalytic transformation vector of purification silencer acoustic performance are analyzed, to find out how the factors influence the muffler performance.Fluid dynamics model of catalytic converter is built by treating catalytic conversion carrier with porous model. The pressure loss in the catalytic converter is calculated and the published experimental data is compared verify the accuracy of the model of the catalytic conversion established in the paper. The flow field distribution, the velocity uniformity coefficient and the pressure loss of the muffler are simulated with the fluid dynamics software FLUENT. The pressure loss of the muffler with different length and different position carriers is studied providing direction for the structure design of purification muffler.According to the above research of the noise reduction unit, the exhaust noise and pressure loss of a mature exhaust system are simulated by using GT-power software. In addition, the exhaust noise of the exhaust system is tested on the actual vehicle to verify the accuracy of the simulation model. According to the conclusion of the analysis above, the exhaust system is improved by adding the carrier, and the exhaust noise and pressure loss are simulated.