低展弦比高负荷跨音速冷却涡轮特性的计算方法

本文在AMDC叶栅损失公式基础上引进了KQ系统,根据高负荷跨音速的特点,对AMDC超临界波阻公式作了修正,选用了合适的栅后气流角公式。用一元可压缩轴对称理论推导了冷气同主气流掺混公式。最后给出高亚音速和跨音速模型涡轮特性以及低展弦比高亚音速冷却涡轮设计点性能和试验结果的比较,精度为1％。

A PREDICTION METHOD FOR CHARACTERISTICS OF COOLED TRANSONIC TURBINES WITH LOW ASPECT RATIO AND HIGH LOAD

At present,advanced aircraft turbines make a feature of low aspect ratio,transonic flow in cascade passage,high aerodynamic load and intensive cooling.In order to predict their characteristics the AMDC formula for cascade loss is corrected on the basis of the so-called KQ system（3）as formula（3）.In accordance with the experimental results of transonic cascades obtained in our country,the AMDC formula for supercritical wave drag is then modified into formulas（4）and（5）for transonic and high subsonic turbines respectively. For the sake of eliminating the cascade choke conditions which do not exist in fact but often occur in calculation,a suitable relation for the flow angle at cascade exit is proposed.The prediction method takes into account the various operating conditions,including subcritical,critical and supercritical expansions,limit supercritical expansion and limit loading,and a computer program has been written.The characteristics of a transonic and a high subsonic turbine models and the design performances of a cooled turbine with low aspect ratio have been predicted with this method,and compared with test results in good agreement.It is shown that the accuracy is about 99 percent.