Numerical Simulation Of Fluid Flow In Catalytic Converter And Its Optimization Design

To meet the demanding emission standards, catalytic converters were required to have high percent conversion, long life, good light-off characteristics and good flow uniformity. Because of the asymmetry of flow, flow would separate along the wall of the expansion tube, and this phenomenon would result in uneven temperature distribution. Moreover, the asymmetry of flow caused catalyzes invalidation easy, and reduced the overall conversion efficiency. Consequently it was necessary to understand the flow behavior inside the converter and optimized the configuration. The CFD software was used to simulate the internal flow of catalytic converters, and focused on the impact of factors on the flow characteristics, such as the catalytic converter structure.The structure of catalytic converters was described; the performance evaluation and related issues were discussed. The mathematical models of gas flow in the catalytic converters were established, including flow control equation, the turbulent transport model and carrier flow model. The distributions of the air flow with conventional shaped carrier in the catalytic converters were simulated. Focused on the influence of the expansion tube structure of catalytic converters, air speed and the carrier parameters to the flow vector distribution.The results showed that considering the flow characteristics and the size of catalytic converters, the expansion tube angle between40°to 60°was most suitable. The flow rate influenced the flow performance clearly. The cavity ahead of the carrier was good for gas flow. The length of carrier also influenced the flow performance, so it should be determined after comprehensive consideration. The results in this paper can provide guidance for actual application.