某型航空活塞发动机排气门的对称烧蚀机理

基于统计显示某型航空活塞发动机运行中出现的大量排气门烧蚀故障案例中烧蚀位置均基本呈两点对称分布在气门头部两侧的现象。通过测量排气门密封面附近气门体的实际运行温度,获取了该型发动机上气门运行温度与排气温度（EGT）之间的对应关系,进一步结合该型发动机的结构设计和实际运行环境分析了这种气门烧蚀点对称分布的机理。研究表明:气门偏摆引起气门密封面温度周向对称性分布不均和运行中过度调贫使气门密封面温度过高是排气门对称烧蚀的主要原因。据此提出以EGT为参照限制调贫幅度的方案,经70 000飞行小时实践验证表明故障得到了完全解决。 

Symmetrical ablation mechanism of exhaust valve at a certain aero piston engine

By measuring actual operating temperature of exhaust valve body near the valve sealing surface, the corresponding relationship between valve operating temperature and exhaust gas temperature (EGT) at this engine was obtained, and the mechanism of symmetrical distribution of valve ablation point was analyzed in combination with the engine structural design and actual operating environment. Results showed that the valve deflection led to uneven circumferential symmetry distribution of valve sealing surface temperature and the high temperature of valve sealing surface due to excessive leaning in operation, bringing about exhaust valve symmetrical ablation. Based on this, solution of limiting the leaning range in operation with EGT as reference was put forward, and the 70 000 flight hours practical test showed that the fault has been completely solved.