环形涡轮动叶栅旋转效应数值研究

Numerical Investigation on Rotating Effects for an Annular Turbine Rotor Cascad

关键词:  旋转效应  机匣相对运动  翼型冠  间隙泄漏

Key words:  Rotating effect  Casing relative rotation  Winglet shroud  Tip leakage flow

摘要:

为揭示动叶旋转与机匣相对转动对涡轮叶栅流场结构和气动性能的影响，针对平顶和翼型冠叶顶的LISA1.5级涡轮动叶片，开展了三维数值模拟研究。结果表明:平顶叶栅中，机匣相对转动能降低泄漏损失，但通道涡强度增大，旋转离心力和科氏力亦对旋涡位置和尺度产生影响；叶顶结构不同会影响各转动条件下的损失变化规律，相对于动叶旋转工况，机匣相对转动可使平顶叶栅出口损失降低3.62%，但使翼型冠叶栅损失提高12.11%；在间隙泄漏流流量方面，不论是平顶叶栅还是翼型冠叶栅，机匣相对转动时叶顶泄漏流量最低，动叶旋转工况次之，静止工况最大。实验中用机匣相对运动代替动叶旋转在研究泄漏流特征时具有一定的合理性，而对于研究旋转效应对通道涡的影响方面则会产生误差。

Abstract:

Three-dimensional numerical simulations were conducted to investigate the effects of rotor rotation and casing relative motion on flow structures and aerodynamic performance for the LISA one-half-stage turbine rotor blade with a flat tip and a winglet shroud tip. Results indicate that for the flat tip， the relative motion can reduce the tip leakage loss， while enhances the intensity of the upper passage vortex. Meanwhile， the rotational centrifugal and Coriolis forces also affect the location and size of vortices. Different tip configurations affect the varying trends of the loss for different rotational cases. Compared to the rotor rotation case， the casing relative motion reduces the loss by 3.62% for the flat tip， while it enlarges that by 12.11% for the winglet shroud tip. However， for the rotor blade with either the flat or the winglet shroud tips， the casing rotation case possesses the lowest tip leakage mass flow rate， followed by the rotor rotation and the stationary cases. The use of relative moving casing to imitate rotating blades in experiments may be reasonable for evaluating the tip leakage flow， while it is not appropriate for auditing the impact of rotating effects on the loss associated with the passage vortex.