二冲程柴油航空发动机混和扫气数值仿真

Numerical Simulation of Mixed Scavenging Methods for Two-stroke Diesel Aero Engines

为建立某型二冲程柴油航空发动机气缸内部三维扫气模型和缸内气相流动数学模型,并对气口结构进行分析,采用分块耦合方法和应用黏接技术对模型进行网格划分,使用GT-power获取仿真边界条件,利用Fluent软件对缸内气体流动进行三维数值模拟。研究结果表明:横流扫气在弱流动区域容易形成扫气盲点;回流扫气可以形成较好的径向涡流,但轴向涡流速度较低,降低扫气效率;混合扫气能减小扫气盲区,形成较好的螺旋涡和速度较高的轴向涡流,与回流、横流扫气相比,排气速度提高12.6%和125.2%,极大地提高了扫气效率。

This paper establishes a three-dimensional scavenging model and a gas flow mathematical model of the inner cylinder forone type of two-stroke diesel aero engine, and analyzes the structure of the gas ports. The calculation domain of the model is meshedby the methods of the multiple block coupling and bonding technology, and the boundary conditions are set by the GT-power. TheFluent software is applied to simulate the three-dimensional gas flow in the inner cylinder. The research results show that the crossscavenging easily produces scavenging blind spots at the weak flow area; the loop scavenging can form a preferable backflow at theradial direction, but the axial velocity is lower, decreasing the scavenging efficiency; The mixed scavenging reduces the scavengingblind spots and forms better spiral vortexes and higher axial swirls, and increases the exhaust velocity by 12.6% and 125.2%,respectively compared with the loop scavenging and the cross scavenging.