柴油机进排气过程的三维数值模拟

3D numerical simulation of intake/exhaust process in diesel engine

利用瞬态可压缩黏性流体微分方程和k-ε两方程紊流模型,采用有限体积法对某柴油机单缸进排气过程进行了三维数值模拟。计算结果表明:进气过程中缸内涡流的产生是由于进气流带动缸内空气由小涡流转变成大涡流,且大涡流是偏心的;排气涡流是由于受气门阻力产生气流回旋而生成的,最大气流速度集中在远离排气口的地方;柴油机转速对缸内气流变化影响较大。

Based on differential equations of transient compressible viscosity fluid and К-ε two-equation turbulent model,a 3D simulation of intake/exhaust process in a diesel engine cylinder was done by means of finite volume method.The results show that the intake swirl is formed from the outside to inside,small to big,while the big swirl is ecentric;the exhaust swirl is formed from the flow whirl which generated by valve resistance,and the maximum velocity of the flow is away from the vent;the speed of diesel engine has great influence on the flows characteristics in-cylinder.