涡轮动叶部分吸力侧肩壁凹槽状叶顶气热和冷却性能研究

Aerothermal and Cooling Performance of Turbine Blade Squealer Tip with Partial Suction Side Rim

关键词:  涡轮动叶  凹槽状叶顶  吸力侧肩壁  气热性能  气膜冷却

Key words:  Turbine blade  Squealer tip  Suction side rim  Aerothermal performance  Film cooling

摘要:

为了获取高性能的燃气涡轮动叶叶顶结构和气膜冷却布局，采用数值求解三维Reynolds-Averaged Navier-Stokes（RANS）方程和标准k-ω湍流模型的方法研究了涡轮动叶部分吸力侧肩壁的凹槽状叶顶气热和冷却性能。数值模拟得到的动叶平叶顶传热系数与实验数据吻合良好，验证了数值方法的准确性。对比0.95吹风比时动叶凹槽状叶顶沿中弧线和近压力侧布置的2种气膜冷却布局的叶顶泄漏流动形态、传热系数和气膜冷却有效度，指出近压力侧的气膜冷却布局B的总压损失大于沿中弧线的气膜冷却布局A；但近压力侧的气膜冷却布局B具有更好的冷却效果。基于近压力侧气膜冷却布局的凹槽状叶顶结构，通过切除尾缘处不同轴向长度的吸力侧肩壁，设计了5种不同的部分吸力侧肩壁的叶顶结构。结果表明：切除10%吸力侧肩壁的Case 7能有效降低总压损失，平均总压损失系数相比完整肩壁的Case 2降低了6.3%；叶顶净热流密度减少和传热系数分布与Case 2基本相同，尾缘处的冷却效率因冷气受到压制附着于叶顶而提高。

Abstract:

In order to obtain high-performance gas turbine rotor blade tip structure and film cooling layout，the effects of partial suction side rim on the aerodynamics and heat transfer cooling performance of the turbine blade squealer tip using three-dimensional Reynolds-Averaged Navier-Stokes （RANS） equations and standard k-ω turbulence model were investigated. The numerical heat transfer coefficient of the turbine blade flat tip was well agreement with the experimental data. The accuracy of the employed numerical method was validated. The tip leakage flow pattern， heat transfer coefficient and film cooling effectiveness of the intact rim tip at blowing ratio 0.95 for two different film cooling layouts with film holes along the mean camber line and near the pressure side were compared and analyzed. The results show that the total pressure loss of layout B with film holes assigned near the pressure side is higher than layout A with film holes arranged along the mean camber line， but layout B has a better tip cooling effect. Based on the intact rim tip with layout B， five partial suction side rim tips were designed by cutting off the suction side rim of different axial lengths near the trailing edge. The results show that compared to Case 2 with intact rim， the averaged total pressure loss coefficient of Case 7 with 10% suction side rim removed drops by 6.3%， while the distribution of the tip heat transfer coefficient and neat heat flux reduction are basically same with Case 2， only the cooling efficiency at the trailing edge is improved since the coolant is suppressed and forced to tip surface.