中重型卡车催化消声器流场特性

运用Fluent软件计算了不同进气端结构和形状的中重型卡车催化消声器载体前端面进气均匀性和进出口总压差, 分析了其流场特性。计算结果表明: 催化消声器流场特性与发动机排气量有关, 载体前端面进气均匀性和进出口总压差对于分析流场特性至关重要; 添加挡板后载体前端面进气均匀性和进出口总压差均增大, 添加竖挡板的流场特性最佳; 进气管直径收缩40mm和排气管直径扩张40mm的流场特性较好; 当发动机转速分别为900、1 900r·min^-1时, 催化消声器优化后载体前端面进气均匀性比优化前分别提高了1.2%、1.6%, 进出口总压差比优化前分别降低了57.5%、63.9%, 结构优化对降低进出口总压差效果明显; 与桶型催化消声器相比, 箱型催化消声器的载体前端面进气均匀性增加; 选择催化消声器还应考虑空间布置与利用效率。

Flow field characteristics of catalytic muffler for medium-heavy duty truck

Aiming at catalytic mufflers with different air inlet structures and shapes of mediumheavy duty truck, the air inlet uniformity of carrier front face and the total pressure difference between the inlet and outlet were calculated by Fluent software, and the flow field characteristics were analyzed.Calculation result indicates that the flow field characteristics of catalytic muffler are related to engine exhaust.The air inlet uniformity of carrier front face and the total pressure difference between the inlet and outlet are very important for analyzing the flow field characteristics.The air inlet uniformity and the total pressure difference increase after adding baffle, and the flow field characteristics are best after adding erect baffle.The flow field characteristics are good when inlet pipe diameter shrinks by 40 mm and outlet pipe diameter expands by 40 mm.After optimizing catalytic muffler, the air inlet uniformities of carrier front face respectively increase by 1.2%and 1.6%, and the total pressure differences between the inlet and outlet respectively decrease by 57.5%and 63.9%compared to the values before optimization when engine rotation speeds are 900r·min-1 and 1 900r·min-1 respectively, which shows that structure optimization significantly decreases the total pressure difference.Compared to barrel shape catalytic muffler, the air inlet uniformity of carrier front face for box shape catalytic muffler increases.Spatial arrangement and utilization efficiency should be considered as well forchoosing catalytic muffler.