轴向轮缘密封导流段几何结构对涡轮级气动冷却特性影响的数值研究

Numerical Investigation on the Effects of Rim Seal Diversion Configurations on Aerodynamic and Film Cooling Performances of Turbine Stage

以轴向轮缘密封为研究对象,在传统直缝密封间隙结构的基础上,通过改变轴向外齿间隙区域的几何型线,设计了双曲线、椭圆及圆型密封导流段结构,数值求解了三维RANS方程组和SST湍流模型,并且系统深入研究了这4种不同导流段几何结构下轮缘密封射流对涡轮级的气动性能,以及对下游动叶端壁冷却性能的影响规律。研究结果表明:所设计圆型、椭圆型以及双曲型导流段结构均可提高涡轮级整体气动性能;圆型密封导流段结构具有最佳的气动性能以及端壁气膜冷却效果。相比于直缝型导流段结构,采用圆型导流段结构在相同的冷气流量下,涡轮级效率可提高约0.23%;在动叶前缘轮缘密封射流所覆盖的冷却区域,采用圆型导流段结构时冷却效率可提高约20%。

In this investigation, the effects of rim seal diversion configurations on the aerodynamic and film cooling performances of turbine stage were analyzed with axial rim seal as the research object. Firstly, hyperbola, ellipse and circle rim seal diversion configurations were designed based on the conventional axial rim seal configuration. Three-dimensional Reynolds-averaged Navier-Stokes(RANS) equations, coupled with a fully-developed shear stress transport(SST) turbulent model from Ansys-CFX, were utilized to evaluate the influence of rim seal diversion configurations on the interaction of the hub leakage flow with the mainstream in the turbine stage. The results show that all the three diversion configurations of hyperbola, ellipse and circle rim seals could improve the turbine efficiency compared with axial seal. The circle rim seal provides the best aerodynamic and film cooling performances of turbine stage. Compared with axial seal, the circle rim seal could improve the turbine efficiency by 0.23% at the same sealing flow rate, and it also improves the film cooling efficiency by 20% in the front of rotor hub platform.