消声器触媒前端喇叭口流场数值模拟

Numerical simulation of flow field for muffler catalyst front-end bell mouth

针对消声器触媒前端喇叭口结构选型问题,选取某消声器触媒为研究对象,采用CFD分析方法对消声器触媒前端喇叭口流场进行数值模拟研究,分析两种规格触媒(直径45,52 mm)中喇叭口不同长度及形状对流场特性的影响。结果表明:触媒段最大合成速度随喇叭口长度增大而减小,轴向速度及压降变化不大,采用长斜面喇叭口可以减小最大合成速度值,降低废气对触媒部件的破坏;无台阶长斜面的喇叭口流场更稳定顺畅,且压降相比有台阶长斜面的压降低。结合流场对比分析结果,建议45 mm触媒结构采用长斜面喇叭口,且喇叭口长度最好不小于80 mm;52 mm触媒结构建议选择无台阶长斜面喇叭口,且喇叭口的长度不小于100 mm。该研究结果可为触媒前端喇叭口尺寸参数的选择提供仿真数据支撑及理论指导。

In view of the structure selection of the front-end bell mouth of the muffler catalyst,a muffler catalyst is selected as the research object.The flow field of the front-end bell mouth of the muffler catalyst is simulated by CFD.The influence of the different length and shape of the bell mouth on the flow field characteristics of the two types of catalyst(45 mm and 52 mm in diameter)are analyzed.The results show that the maximum synthesis speed of catalyst section decreases with the increase of the bell mouth length,and the axial speed and pressure drop change little.The long bevel bell mouth can reduce the maximum synthesis speed value and reduce the damage of waste gas to catalyst components;the bell mouth flow field without long bevel of step is more stable and smooth,and the pressure drop is lower than that with long bevel of step.Combined with the results of flow field comparison and analysis,it is suggested that the 45 mm catalyst structure should adopt a long inclined bell mouth,and the length of the bell mouth should be no less than 80 mm;the 52 mm catalyst structure should choose a long inclined bell mouth without steps,and the length of the bell mouth should be no less than 100 mm.The research results can provide simulation data reference and theoretical guidance for the selection of the size parameters of the catalyst front-end bell mouth.