增压状态下汽油机进气道性能评价及流通特性分析

针对某增压汽油机开发过程中进气道性能评价问题，建立了三维稳态及瞬态仿真模型，研究了增压状态下进气道无量纲流量系数、总体流量、缸内流动及喉口流速的变化规律．结果表明：随着进气压差的增大，气道无量纲流量系数明显降低，最大降幅达11％，但总体流量仍呈增长趋势；增压以后，气流速度大幅提升，大气门升程下，气门阀座处产生分离涡旋运动，加剧缸内扰动，有利于加快燃烧速度，降低爆震倾向；同时，气道流通截面流速增大，最高进气马赫数为0．46，处于安全范围．综合各项数据，判定该气道性能满足增压机型需求．

Intake Port Performance Evaluation and Flow Characteristic Analysis of Gasoline Engine Under Boosted Condition

In order to evaluate the performance of intake port during the development of a turbocharged gasoline en- gine, three-dimensional steady and transient simulation models were developed. The change regulations of no- dimensional discharge coefficient, total mass, in-cylinder flow structure and throttle flow velocity were investigated under boosted condition. Results show that with intake port pressure drop increasing, the no-dimensional discharge coefficient of intake port decreased obviously, and the maximal decline reached 11%. However, the total mass flow was increasing all the time. After boosting, flow velocity increased sharply. At high valve lift, flow separated on the short side of the port, and generated a more highly disturbed flow structure, which was helpful for accelerating bum rate and achieving good knock resistance. Meanwhile, throttle flow velocity increased apparently, and the intake flow Mach number was 0.46 to the highest point, which is still considered to be reasonable. As a result, the port is judged to be suitable for the turbocharged engine.