甲醇发动机稳压腔结构对进气的影响研究

Study on Effect of Pressure Stabilizing Cavity Structure on Intake of Methanol Engine

针对甲醇汽车发动机进气不均匀的问题,建立进气系统三维模型,运用湍流方程,对甲醇汽车发动机侧置进气系统内流场进行仿真计算,对比了不同稳压腔参数下的流线分布和各歧管中的质量流量,分析流场的流动特性,进而研究进气系统的进气均匀性。结果表明,进气总管与稳压腔的夹角增大有利于提高气体流动性,但夹角过大会产生较多涡流,在5°时进气均匀性最好;稳压腔壁面倾角增大,导致稳压腔容积增大,有利于提高充气系数,但倾角过大会导致腔内流体速度梯度变化大,在2°时,发动机进气均匀性最好。

Aiming at the problem of uneven intake of methanol automobile engine, a three-dimensional model of intake system is established, and the flow field in the side intake system of methanol automobile engine is simulated and calculated by using turbulence equation. The streamline distribution and mass flow in each manifold under different pressure stabilizing chamber parameters are compared, the flow characteristics of flow field are analyzed, and then the intake uniformity of intake system is studied. The results show that the increase of the angle between the inlet manifold and the pressure stabilizing chamber is beneficial to improve the gas fluidity, but more vorticity will be generated when the inlet manifold is too large. The uniformity of the inlet is the best when the inlet manifold is 5 °. The increase of the wall inclination of the pressure stabilizing chamber leads to the increase of the volume of the pressure stabilizing chamber, which is beneficial to improve the charging coefficient. However, the excessively large inclination leads to the great change of the velocity gradient of the fluid in the chamber. The inlet uniformity of the engine is the best at 2 °.