涡轮叶片凹槽状叶顶非定常流动传热特性的数值研究

Numerical Investigations on Unsteady Leakage Flow and Heat Transfer Characteristics of Turbine Blade with Squealer Tip

为了研究涡轮叶片凹槽状叶顶的非定常流动传热特性,以GE-E3第一级静叶和动叶为研究对象,采用ANSYS-CFX数值求解三维Reynolds-Averaged Navier-Stokes(RANS)和标准k-ω紊流模型。数值预测的叶顶换热系数分布与实验数据吻合良好,从而验证了数值方法的可靠性。数值计算结果表明:静叶尾迹对动叶顶部的流动和换热特性影响显著。压力面侧前缘区域和吸力面中间位置的流场受动静干涉影响显著。叶顶表面的换热系数脉动主要出现在靠近前缘的凹槽底部表面和再附着线附近及吸力面侧肩壁。靠近动叶尾缘区域的换热系数脉动同时受动静干涉作用和下游流场的影响。定常计算得到的换热系数在前缘冲击区和分离线附近高于非定常时均值,在压力面侧肩壁附近小于非定常时均值。定常计算得到的平均换热系数要高出非定常计算结果3.5%。

In order to investigate the unsteady heat transfer characteristics of the turbine blade with squealer tip,the first stage of GE-E3 turbine was implemented and the numerical simulations were conducted using three-dimensional Reynolds-Averaged Navier-Stokes（RANS） and standard k-ω turbulent model based on the CFD software ANSYS-CFX.The numerical results agree well with the experimental data on the experimental blade tip.The accuracy of the utilized numerical approach has been validated.The numerical results show that the tip flow structure and the heat transfer performance of blade tip are significantly affected by the wake flow.The flow field in the regions near the pressure side leading edge and the middle chord suction side is greatly influenced by the rotor-stator interaction.The fluctuations of the heat transfer coefficients are observed near the leading edge impingement region,the reattachment line and the suction side squealer rim.The heat transfer coefficients on the blade tip near the trailing edge are affected by the downstream flow field and the rotor-stator interaction.The level of heat transfer obtained from the steady simulation is enhanced near the reattachment line and the impingement region,however which is reduced near the pressure side squealer rim by comparison with the timeaveraged results.The average heat transfer coefficient of the blade tip surface obtained by steady result is 3.5%higher than the unsteady time-averaged result.