大子午扩张涡轮的根部型线研究

Investigation on root blade profile of a large meridional expansion turbine

大子午扩张涡轮具有外壁侧来流易分离、导叶出口径向压差较大等特点,对根部型线优化改型和原型进行全三维数值模拟,分析了下端壁叶型型线对流动的影响,并研究了根部型线设计特点.结果表明:优化根部型线,能够合理的对栅前流量径向分布进行调整,减弱甚至消除顶部来流分离,改善顶部流动;同时,此叶型也能合理的改善出口马赫数分布以及出口压力径向分布,减弱和消除吸力侧出口S1面分离的径向流动,改善根部流动.

The investigation focused on the design characteristic of root blade profile in the large meridional expansion turbines.And,the effect of root blade profile optimized design on the flow separation at vane inlet and radial pressure distribution at vane outlet was also studied.With the commercial numerical simulation solver,NUMECA,optimized design of root blade profile was applied into a large meridional expansion turbine.Then full three-dimensional numerical simulations on the original and optimized profiles were carried out.The numerical results show that,wider profile and convergent-divergent root profile would adjust radial distribution of massflow at inlet,weaken or even eliminate incoming flow separation at the upper endwall,hence controlling the flow loss in shroud;meanwhile,such profiles could improve mach number distribution and radial distribution of pressure at outlet,weaken or even eliminate radial flow of S1 section separation in the suction side at exit,thereby reducing flow loss in hub.