透平叶栅非轴对称端壁的设计与优化

Design and Optimization of Non-axisymmetric Endwall in Turbine Cascades

采用NURBS曲面造型方法,在轴对称端壁上叠加径向高度变化量构造非轴对称端壁。采用最优拉丁超立方设计的方法,经过两轮实验设计,寻求性能较优的设计方案。结果分析表明:基于最优拉丁超立方的实验设计方法,定向搜寻透平叶栅的非轴对称端壁优化设计方案,是可行的。与圆柱端壁相比,优化后涡轮叶栅通道出口面积平均二次流动能减小5.48%,总压损失系数减小了1.63%,端壁换热状况局部有改善。非轴对称端壁通过改变端壁的静压分布削弱了涡轮叶栅通道中马蹄涡、通道涡的强度。非轴对称端壁使通道内靠近进口段和出口段端壁换热被削弱,尾迹区换热有所增强。

Non-uniform Rational B-spline Surface （NURBS） is used to design non-axisymmetric endwall through adjusting the radial protrusion of axisymmetric endwall in turbine cascade. Design of experiment with optimal Latin Hypercube is applied to construct non-axisymmetric endwall scenarios for a high pressure turbine rotor. Results show that two-step direct search among tile designing space constructed by the optimal Latin hypereube method is an efficient way to obtain optimal endwall contour. Compared with the axisymmetric endwall, non axisymetrie endwall reduces 5.48% of the area averaged secondary kinetic energy and 1.63% of the relative total pressure loss at the passage exit. The heat transfer coefficients on endwall are also reduced in some areas. The non axisymetric emdwall changes the pressure distribution on the endwall and weaken the strength of tile horseshoe vortex and the passage vortex in turbine cascade passage. Heat transfer decreases in tile forward part of passage while increase in the aft part of passage. Heat transfer near the trailing edge is increased.