一级半轴流式透平的非定常流动干涉与时序效应

Interaction and Clocking Effect of Unsteady Flow in a One and a Half Axial-flow Turbine Stage

对Aachen一级半轴流式透平进行了全三维粘性非定常流动数值模拟,分析了相邻叶排间主要干涉现象和时序效应.结果表明:相邻叶排的压力有势场存在势干涉,动叶与第2列静叶间的势干涉更为强烈,势干涉定量反应为静压波动,并以一定的速度向上、下游传播;被动叶截断的上游静叶尾迹在动叶通道中发生变形而周期性地出现在绝对坐标系的固定位置,为时序效应的产生创造条件,通过分析动叶出口熵值的时空分布图可确定下游静叶的最优时序位置;透平级出口非定常熵值定性决定了非定常效率,为透平的非定常优化设计提供了目标参数.

The unsteady flow in a one and a half of Aachen axial-flow turbine stage was investigated by full three-dimensional viscous numerical simulation, and the main interaction phenomenon of adjacent blade rows and clocking effect were discussed. Results indicate that between adjacent blade rows the interaction of pressure potential field happens, which is more intense between the rotor and the second stator. The interaction of pressure potential field is quantified by the fluctuation of static pressure on the surface of blade and propagates upstream and downstream at certain speed respectively. Truncated by the blade, the wake caused by upstream stator, which is distorted in the rotor passage occurs at certain position in the absolute coordinate system periodically, which creates a condition for clocking effect. The best clocking position for the second stator can be determined through analyzing the space-time diagram of entropy at the exit of rotor. Qualitatively, the entropy at the exit of the turbine decides the efficiency of turbine stage, which provides a new objective parameter for unsteady optimization and design of turbines.