多孔介质模型在发动机进气道数值模拟计算中的应用

Application of Porous Medium Model in Numerical Simulation of Engine Intake Port

针对传统气道数值模拟计算方法与目前国内广泛采用的涡流动量计式台架的差异,提出了基于多孔介质模型的气道计算方法,以考虑试验缸筒以下稳压箱及蜂窝器对气流的影响。通过累加涡流比测量位置处各网格单元的微角动量矩,转化为气道涡流比值。研究结果表明:基于多孔介质模型的方法可以提高气道模拟计算精度,尤其是涡流比的计算精度。以各气门升程区间所占进气行程曲轴转角比例为比例系数,定义了新的平均流量系数和平均涡流比计算公式,基于多孔介质模型的方法计算获得的平均流量系数和平均涡流比相对试验结果的误差分别为3.29%和-11.39%,相对传统计算方法的11.50%和-26.63%,精度明显提高。

Aiming at the difference between the traditional intake port numerical simulation and the currently used swirl momentum experiment rig, a new computation method based on the porous medium model was proposed to consider the effects of plenum and honeycomb on intake flow. Through the accumulation of micro angular momentum of individual grid cell, the swirl ratio could be acquired by some conversion algorithm. The research results show that the new computation method of porous medium model can improve intake port simulation accuracy, especially for swirl ratio. Taking the ratio of crankcase angle to the whole intake stroke crank angle as a coefficient, a new formula of mean flow coefficient and mean swirl ratio can be defined. By use of the new computation method, the relative errors of simulated mean flow coefficient and mean swirl ratio are 3.29%、-11.39%, compared to the corresponding experiment results, and simulation accuracy improves significantly when compared to the relative errors of 11.50% and -26.63% by traditional method.