轴流涡轮转子下游多边界盘腔燃气入侵数值研究

Numerical Study on Gas Intrusion in Multi Boundary Disk Cavity Downstream of Axial Flow Turbine Rotor

研究涡轮燃气入侵对发动机性能和可靠性具有重要意义,但现有研究多集中于动叶上游盘腔,需要深化对动叶下游盘腔燃气入侵问题的研究。以某高压涡轮及其下游二次空气系统为研究对象,采用三维定常数值模拟探究了适用于转子下游多边界盘腔燃气入侵仿真方法,分析了不同压比下封严流量和燃气入侵特性,并研究了盘腔内部流动机理。结果表明:采用压力边界条件的仿真结果更符合多边界盘腔流动现实。各封严流量随盘腔进口压力增加而增大,但梯度逐渐减小,轮缘封严达到最小流量后基本呈线性变化,而盘腔内部封严流量趋于稳定。在阻止主流入侵的最小封严流量附近,轮缘封严压力分布难以判断主流是否入侵盘腔内部,而轮缘封严齿间流体温度是判断主流燃气入侵盘腔内部的重要参数。

Research on turbine ingestion is important to engine performance and reliability.Most research focuses on the upstream disk cavity, but study on the gas ingress in aft-disk cavity is necessary.Taking a high pressure turbine and downstream secondary air system as the research object, the gas ingress simulation method that is suitable for aft-disk cavity with multiple boundaries is studied by steady simulation method.Sealing flow rate, ingestion characteristics and flow mechanism in the cavity are also analyzed under different pressure ratio.The results show that pressure boundary is more appropriated than mass flow boundary for multiple boundaries cavity simulation.Sealing flow rate increases with the increase of inlet pressure, but the gradient decreases gradually.After the minimum flow of rim seal is reached, the rim sealing flow changes linearly and the flow of inner seals tends to be stable basically.Near the condition of minimum rim sealing flow, ingestion can be recognized by the fluid temperature in the seal rim rather than the vicinal pressure distribution.