刮削作用对涡轮转子机匣通道涡形成的影响

Influence of scrapping effect on formation of casing passage vortex in turbine rotor

采用数值方法求解耦合剪切应力输运(SST)湍流模型的雷诺平均Navier-Stokes方程组,研究了不同间隙尺寸下GE-E3高压涡轮第一级转子内刮削作用对机匣通道涡形成和发展的影响。通过与轮毂通道涡结构的对比,发现机匣通道涡层次结构与经典二次流理论存在明显的差异,并对该差异形成的原因进行了深入探索。结果表明:叶顶对机匣边界层的刮削作用在机匣通道涡的形成过程中占主导作用,刮削作用使得流向叶片吸力面的来流机匣边界层在交汇点区域从内层向外层卷起,形成层次结构相反的机匣通道涡;叶顶浸入比值是影响转子机匣通道涡形成的重要参数,随着比值的增大,机匣通道涡损失先增大后减小;只有在间隙尺寸较大情况下,叶尖间隙的"抽吸作用"才能抑制机匣通道涡的发展。

Investigations into the influence of scrapping effect on the formation and development of rotor casing passage vortex were carried out in the first-stage high pressure turbine（HPT）rotor of GE-E3 with various tip clearance by solving Reynolds-averaged NavierStokes equations with shear stress transport（SST）turbulence model.Compared with the hub passage vortex,the casing passage vortex was found different from the classical theory of endwall secondary flow,and the origin for these differences was explored.The results indicated that：the scrapping effect of blade tip on the casing boundary layer played a dominant role in the formation of casing passage vortex.It made the inner part of inlet casing boundary layer flow towards the merging region on suction surface,roll up and wrap the outer part,and a casing passage vortex was developed with reverse construction.Immerging ratio of blade tip was an essential parameter affecting the formation of casing passage vortex,and the loss could increase first before decrease as the tip clearance size increased.Only in the situation of large tip clearance size could the＂suction effect＂of tip clearance suppress the development of casing passage vortex.