涡轮叶尖泄漏流被动控制数值模拟

结合基于密度修正的采用雷诺应力湍流模型加壁面函数的三维计算流体力学程序,通过在叶尖吸力面表面加肋条的被动控制方法以期减小叶尖间隙泄漏流动带来的损失,对某一轴流涡轮转子叶尖间隙泄漏流场的被动控制进行了数值模拟研究,并详细分析了在不同肋条高度下泄漏流场细节,最后计算了涡轮效率。结果表明,在涡轮叶尖表面沿吸力面边缘镶肋条对泄漏流动进行被动控制,相对于与其相对叶尖间隙高度相等的基本间隙流场,涡轮效率增大;肋条高度对涡轮效率有较大影响,相对等绝对叶尖间隙高度的基本流场,增大肋条高度可以提高涡轮效率。在叶尖间隙区域前半部,肋条对泄漏流动的阻挡作用使得在叶尖表面出现回流区,阻碍泄漏流动;在叶尖间隙区域后半部,回流区消失。

Numerical simulation of passive control on tip leakage flow in axial turbine

In order to reduce the tip leakage loss by means of the injection active control measure in tip platform,a dense-correction based,3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds stress model and wall function was used to simulate the effects of the passive control of a partial squealer tip around suction side on the tip leakage flow in a turbine rotor.With different rim height in a squealer tip,the effect of squealer tip on the tip leakage flow,especially on the efficiency,was sequentially simulated and compared with the baseline flow without partial squealer tip.The results show that the passive control on tip leakage flow using a partial squealer tip around suction side can increase the turbine efficiency relative to that of the baseline flow with equivalent relative tip clearance height.The height of suction side rim has more influence on the turbine efficiency,and the increase of rim height can result in the increase to turbine efficiency relative to that of the baseline flow field with equivalent absolute tip clearance height.Recirculation region formed by the blockage on tip leakage flow exists in the former half of the tip platform near the rim,while it disappears in the later half of the tip platform.