高压涡轮导向器叶片冲击冷却数值研究

Numerical Study on Impinging Cooling for a High-Pressure Turbine Blade

关键词:  冲击冷却  导流片  气热耦合  射流孔

Key words:  Impinging cooling  Deflector  Conjugate heat transfer methodology  Impinging hole

摘要:

针对高压涡轮导向器叶片表面温度过高的情况,采用在叶片内安装导流片并布置射流孔的方式对高温叶片进行冲击冷却,运用带转捩的Transition k-kl-ω模型完成了气动和传热的三维耦合计算分析,研究了改善冲击冷却效果的方法和途径,实现在保持冷却气体流量不变条件下,提高冷却效果、降低材料的性能要求。计算结果表明:在一定孔径范围内,射流孔数和孔径满足(4n-1)D=h的关系式时,沿叶高方向能满足冷却要求；选择在压力面开3列、吸力面开4列射流孔,能满足叶片中弦区域冷却要求,采用劈缝排气方式可以消除尾缘高温现象；导流片与叶片间距z_n/D在1.71~2.57变化时,对叶片内外表面平均温度影响不大,而随间距变小,叶片内外表面最高温度降低,最低温度则会升高；随冷却气体温度降低或流量增加,冷却效果会更好。 

Abstract:

Methods of installing deflector in the blade and arranging jet holes are adopted for high temperature blades impinging cooling on account for the problem of the high surface temperature for a high-pressure turbine blade.Three-dimensional conjugate heat transfer methodology analysis is completed using Transition k-kl-ω model.Methods of improving the effect of impinging cooling are discussed in order to achieve the goal of enhancing the cooling effect and reducing the performance requirements for the material with the same amount of gas flow rate. The computational results show that if the number of holes and the diameter meet the relationship(4n-1)D=h, the temperature along blade height can satisfy the cooling requirements for certain conditions.Opening three jet holes in the pressure side and four in the suction side, cooling requirements of the leaves chord region can be satisfied, and the exhaust heat phenomenon of trailing edge can be eliminated using the way of splitting seam.The inner and outer average temperature of blade surfaces almost keep the same when the distance of deflector and the blade z_n/D changes between 1.71~2.57.However, with smaller spacing, the maximum temperature will fall and the minimum temperature will rise.The cooling effects will be better with lower cooling gas temperature or higher mass flow rate. 