汽轮机末级动叶片大负攻角工况下的气流激振分析

在小容积流量工况下运行的大功率机组的末级动叶顶部进口气流的负攻角流动易造成叶片压力面的气流分离，在一定条件下会诱发叶片颤振。对一典型平面动叶栅大负攻角下的二维分离流场进行数值分析，得到了详细的流场信息和叶片作用力及力矩与攻角的关系。采用准定常的方法，给出了叶片发生扭转和弯曲振动时，激振流场对叶片的气动功的计算方法，并根据能量法的原理，讨论了判断叶片颤振的方法。

Analysis of Flow Exciting for the Rotor Blade of Steam Turbine Last Stage at Large Negative Incidence

The negative incidence of the inlet flow of last stage rotor cascade under the low mass flow rate condition of steam turbine may result in the flow separation at the pressure surface and cause blade oscillation on certain conditions. In this paper the two-dimensional separation flow field of a typical rotor cascade is numerically analyzed and the flow field information and the correlation of blade force and blade moment with incidence are obtained. Moreover, with the assumption of the quasi-steady flow, the calculation method of the work done by the oscillating flow on blade is presented and the criterion for predicting blade oscillation is discussed on the basis of energy method.