汽轮机静叶栅二次流损失的数值研究

Numerical study of the secondary flow loss in steam turbine static cascade

基于有限元有限体积法和全隐式多网格耦合算法,对某汽轮机高压级有一定扭曲度的静叶栅流场进行了三维稳态数值模拟,分析计算了叶栅通道内上下端壁二次流发展的特点及叶栅的气动特性。计算结果表明,叶栅端壁二次流损失与叶型型面及上下端壁面的汽流情况有密切关系。同时揭示了叶栅通道内的涡系演变特点,发现在流道尾部二次流强度发展迅速,在靠近背弧上下端部附近形成两个明显漩涡区,进而引起总压损失系数和出口汽流角沿叶高方向产生明显变化,这对存在一定扭曲度叶栅的气动特性研究及设计有一定的指导意义。

The paper is based on finite element finite volume method and fully implicit multigrid coupling algorithm,high pressure level of a steam turbine with a certain degree of distortion of the static cascade flow field in three-dimensional numerical simulation of steady-state,the paper analyses and calculates the developmental characteristics of the secondary flow in the lower wall of the cascade channels and the aerodynamic characteristic of the cascade.The calculated results show that the secondary flow loss of cascade endwall is bound up with type surface of leaf type and the lower wall.Meanwhile,the calculated results reveals the characteristic of evolution of vortices in cascade channels,it finds that the strength of secondary flow develops rapidly,two obvious vortex area formed nearly the blade convexity of the upper and lower changes the total pressure loss coefficient and exit flow angle along the leaves high direction,the conclusions are instructive in studying on aerodynamic characteristics of cascade with certain distortion degree and designing.