凹槽状叶顶涡轮叶片传热特性的数值研究

Numerical Investigations on Heat Transfer Characteristics of Turbine Blade with Squealer Tip

关键词:  涡轮叶片  凹槽状叶顶  气膜冷却  传热  数值模拟

Key words:  Turbine blade  Squealer tip  Film cooling  Heat transfer  Numerical simulation

摘要:

采用计算流体动力学软件ANSYS-CFX数值求解三维Reynolds-Averaged Navier-Stokes(RANS)和标准 k - ω 紊流模型研究了涡轮叶片凹槽状叶顶的传热特性。数值预测的平顶部叶顶的换热系数分布与实验数据吻合良好，验证了数值方法的可靠性。计算分析了凹槽深度和肩壁厚度对凹槽状叶顶传热特性的影响，还分析了动叶与机匣相对运动下的凹槽状叶顶无气膜冷却和中弧线布置气膜冷却时的流动换热特性。研究结果表明:在肩壁厚度一定时随着凹槽深度的增加叶顶换热系数降低；在1%叶高的叶顶间隙和2%叶高的凹槽深度及4种肩壁条件下1.0mm肩壁厚度时叶顶换热系数最小。相比于动叶与机匣均静止时，动叶和机匣之间的相对运动能够增强动叶顶部的换热效果；动叶与机匣间的相对运动能够增强前缘处气膜冷却效果，总体来说动叶旋转时的离心力和哥氏力对凹槽状叶顶的气膜冷却效果影响有限。

Abstract:

Numerical investigations on the heat transfer characteristics of the turbine blade with squealer tip was carried out 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 for the turbine blade with flat tip. The accuracy of the utilized numerical approach was demonstrated. Effects of squealer depth and squealer rim width on the heat transfer performance of turbine blade with squealer tip and effects of the relative motion between the blade and casing on the heat transfer characteristics of the squealer tip with film holes located at the camber line on the squealer tip and without film cooling structure were conducted. The numerical results show that the heat transfer coefficient of the blade tip decreases with the increase of the squealer depth at the fixed rim width. The minimization of the averaged heat transfer coefficients of the tip was obtained at the tip clearance with 1% span and squealer depth with 2% span and rim width with 1.0mm among 4 cases. The relative motion between the blade and casing can strengthen the heat transfer performance by comparison of the rotor and casing stationary case. The relative motion between the rotor blade and casing can only strengthen the film cooling performance near the leading edge. The effects of the centrifugal force and Coriolis force on the film cooling performance of squealer tip in total are limited.