排气三通管道分散流流动特性的数值模拟及分析

为减小排气T型三通管道中的局部压力损失,利用FLUENT软件对其分散流动特性进行数值模拟,分析支管与总管流通截面积比、夹角、质量流量比及流体温度对管道总压损失系数的影响规律。结果表明:总管流速和气体温度对总压损失系数影响不大,支管与总管质量流量比却对总压损失系数影响显著;分支管与总管夹角、分支管与总管流通截面比对总管-通支管总压损失系数的影响不明显,但对总管-分支管总压损失系数的影响显著。通过数值模拟和分析建议T型三通管推荐结构为分支管与总管夹角α=45°,分支管与总管流通截面比A3/A1的适宜范围为0.8~1。数值模拟结果与前人研究及试验结果比对,趋势一致,计算精度较高,可为类似汽车排气分流技术开发提供依据。

Numerical simulation and analysis on the dispersed flow characteristics in tee branch pipe of exhaust system

In order to reduce the local pressure loss in T-type tee pipe, a numerical simulation based on FLUENT software was carried out for the dispersed flow characteristics of the tee branch pipe, with the influence analysis on the total pressure loss coefficient under different conditions of the flow area ratio, angle, mass flow ratio and fluid temperature of the branch and main pipes. The simulation results show that the flow velocity and temperature of the main pipe have little impact on the total pressure loss coefficient, but the mass flow ratios of branch and main pipes have important influence; both the angles and flow area ratios of branch and main pipes have little impact on the total pressure loss coefficient of main straight pipe, yet they have significant impact on the total pressure loss coefficient of main-branch pipes. Through numerical simulation and analysis, the structure of tee branch pipe is recommended that angle α of branch-main pipe is 45°, and flow area ratio A3/A1 of branch and main pipes is within the appropriate range of 0.8 to 1. The numerical simulation and experimental results are compared with previous studies, showing the same trend and high accuracy of calculation, which can provide the basis for similar car exhaust diversion technology development.