蒸汽轮机叶片失速颤振的预测

本文移植了轴流压气机叶片失速颤振预测方法中一种半经验方法——变形激盘法,从自激振动的角度分析了蒸汽轮机末级工作叶片在某些工况下动应力突增的故障。本文中计算与实测值间的定性一致表明:末级工作叶片在低负荷状态的动应力突增是由于大负攻角失速颤振所引起的。本文对设计工况附近的动应力增加提出了一种解释,在设计工况叶片可能存在一种目前尚未分类过的“高负荷非失速颤振”。 

PREDICTION OF STALL FLUTTER OF STEAM TURBINE BLADES

The failure of the steam turbine last stage blades by abrupt increment of dynamic stress in some conditions has been analyzed, and it is confirmed that the main cause of this breakdown is self-excited vibration (flutter) of blades. The actuator disk method has been transplated from aeronautics to predict the steam turbine blade flutter. The actuator disk method only deals with the unsteadyflow field in front of and behind the cascade.The governing equation of the flow field is the linearized Ruler's Equation. To determine the constants of the equation solution, the cascade loss is correlated with the experimental data.The comparisons between the predictions and experimental results are acceptable.It is demonstrated that the abrupt increment of the blade dynamic stress at small volumetric flow is caused by large negative incidence stall flutter. It is discovered from the computations that at design conditions there may be a kind of high loaded unstall flutter which still hasn't been defined.