不同喷射方法柴油机进气甲醇预混过程的模拟

采用欧拉气相方程和拉格朗日液滴方程,考虑液滴破裂、蒸发、碰撞、聚合以及液滴的附壁、液膜剥离壁面和气门关闭挤出液膜等现象,建立了柴油机螺旋进气道-气门-气缸的进气喷射甲醇仿真模型.对柴油机进气喷射甲醇的醇气混合进行数值模拟,用于指导双燃料发动机的改造.双燃料发动机的台架试验表明,模型计算的缸内压力与试验值吻合较好.甲醇喷射时刻直接影响本次循环进入气缸的甲醇量,闭阀喷射有利于甲醇在进气过程的雾化混合.在选择甲醇喷射方向时,要以减小甲醇在低温壁面的附壁为原则.甲醇蒸气在气缸里的轴向质量分数分层比径向质量分数分层明显.

Simulation of Diesel Engine Intake Premixed Methanol with Different Injection Modes

Using the Eulerian gas equation and Lagrangian drop equation,a simulation model of intake injecting methanol for a diesel engine with helical port-valve-cylinder was proposed.The model consists of liquid droplet break-up,evaporation,collision and coalescence,as well as wall interaction of liquid droplets and wall film separation and valve seat liquid expelling.Methanol and air mixing process for methanol injected into the engine intake port was simulated to guide the methanol/diesel dual fuel engine modification.Bench test of the dual fuel engine shows that the cylinder pressure of model calculation is good agreement with that of experiment.Methanol injection timing directly affects the cyclic amount of methanol into cylinder.Methanol injection during inlet valve closed will be more readily atomized and mixed in the induction stroke.Methanol injection orientation is determined by the principle of decreasing methanol film on cold wall.Methanol concentration in cylinder is stratified more obviously in cylinder axis direction than that in cylinder radial direction.