涡轮转子叶尖泄漏涡涡核稳定性及控制

以GE-E3第一级涡轮转子为研究对象,对转子叶尖泄漏涡涡核破碎特征和稳定性机理进行了分析和归纳。研究表明:叶尖泄漏涡涡核破碎的动力是离心不稳定性;发生失稳后,涡核区域迅速膨胀,形成低速的回流区;涡核的稳定性取决于螺旋因子和逆压梯度两个因素。然后,从涡核稳定性的角度开展了叶尖泄漏损失控制的研究,计算表明:叶尖叶型的负荷前移能够减少叶片尾缘附近间隙内的横向压力梯度;吸力面喉部位置以后型线拉直能够减少喉道后的扩压系数;通过这两个措施生成的新叶片能够有效地减弱叶尖泄漏涡,抑制涡核的不稳定性,减少叶尖泄漏流损失。

The feature of tip-leakage vortex breakdown and the stability mechanism were analyzed and summarized using the first-stage rotor blade of GE-E turbine. The study indicated that: the breakdown of tip-leakage vortex core was caused by vortex's centrifugal instability; the vortex core expanded rapidly after losing stability and reversed flow was formed; the vortex core stability depended on two factors: swirling number and reversed pressure gradient. After that, the control of tip-leakage loss was carried out from the perspective of vortex core stability. Calculations show that: moving forward the loading of tip blade profile can reduce the pressure gradient; employing straight profile on the suction surface after passage throat can directly decrease the profile diffuse factor; and the redesigned blade by those two methods can obviously weaken the tip-leakage vortex, suppress the instability of vortex core and decrease the tip-leakage losses.