突肩叶尖吸力侧开槽对叶尖间隙流动换热特性的影响

Effects of Squealer Tip Suction Side Cutback on Tip Leakage

关键词:  高压涡轮  叶尖间隙高度  叶尖泄漏流量  叶尖泄漏损失  换热系数

Key words:  High pressure turbine  Tip clearance height  Tip leakage flow  Tip leakage loss  Heat transfer coefficient

摘要:

为了研究突肩叶尖吸力侧开槽对叶尖间隙泄漏流动换热特性的影响，采用标准k-omega两方程模型对不同突肩叶尖形式下的间隙泄漏流动进行了研究，研究的叶顶形状包括全突肩和3种部分突肩叶尖。详细分析了不同叶尖结构在3种间隙高度下的间隙泄漏流场，机匣压比，泄漏流量，总压损失和叶尖表面换热系数。结果表明:吸力侧前缘开槽可以改变前缘附近的间隙泄漏流路径，使得泄漏涡的形成位置后移，从而减小泄漏损失，但是效果微弱；吸力侧尾缘开槽可以改变开槽附近泄漏流体的流动路径，抑制其与主流的掺混，有效减小间隙泄漏损失，研究范围内最多减小8%。吸力侧前缘和尾缘开槽叶尖均会增加间隙泄漏流量，开槽长度越大泄漏流量越大，研究范围内最多增加32%。吸力侧前缘开槽会减小具有高换热系数的突肩表面积，增加凹槽表面换热系数；尾缘开槽会减小突肩表面积，增加凹槽底面的低换热系数区域的面积。

Abstract:

In order to investigate the effects of squealer tip suction side cutback on the tip leakage flow and heat transfer characteristics，the standard k-omega two equation model was used to simulate the tip leakage flow heat transfer characteristics of different squealer tips. The researching tip configurations include a full squealer tip and three partial squealer tips. The leakage flow field，casing pressure ratio distribution，leakage flow rate，total pressure loss and tip heat transfer coefficient of different squealer tips were analyzed under three clearance heights. The results show that the suction side squealer leading edge cutback can change the tip leakage flow path around the leading edge and push the beginning of the leakage vortex backward，so the leakage loss decreases slightly. The suction side squealer trailing edge cutback can change the tip leakage flow path around the trailing edge and suppress the mixing of the leakage flow and the main stream，so the leakage loss decreases effectively，and the maximum reduction is up to 8% at the research range. The suction side leading edge and trailing edge cutback both can increase leakage flow rate，and the leakage flow rate increases with the increase of the cutback length，and the maximum increase is up to 32% at the research range. The suction side squealer leading edge cutback can reduce the squealer surface area which has high heat transfer coefficient and increase the heat transfer coefficient of cavity surface，the trailing edge cutback can also reduce the squealer surface area and increase the low heat transfer coefficient area of cavity surface.