Aerodynamic and cooling performance of a novel step-shaped slot film cooling geometry
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摘要:
为了抑制气膜冷却过程中耦合涡的产生，提出了一种切向出流台阶缝冷却结构，并对其在涡轮导叶吸力面、压力面上布置时的气动性能及冷却特性进行了数值研究。结果表明：在吸力面叶栅通道喉部附近布置时仅使总压损失增加约2%；在压力面布置则能使总压损失、能量损失在低吹风比工况各降低约2.5%，同时出口气流角的增加不到0.1%，而且损失系数和出口气流角对吹风比的变化也不敏感。吸力面、压力面缝后冷却效率均较高，在高吹风比工况平均都有约8%轴向弦长的叶片表面冷却效率接近1.0。
Abstract:In order to permanently reduce the coupling vortices in film cooling, a novel step-shaped slot cooling geometry with tangential coolant ejection was introduced and its aerodynamic and cooling performance was numerically investigated. The effects of slot location at the suction and pressure side of a turbine vane and cooling air blowing ratio on these performances were also analyzed. The results show that slot injection from the suction side near-throat region only increases the total pressure loss by about 2%, while injection from the pressure side decreases both the kinetic loss and total pressure loss by about 2.5% with the air exit angle increasing less than 0.1% for low blowing ratios. Meanwhile, the loss coefficient and the air exit angle are not sensitive to the variation of blowing ratios. Additionally, cooling effectiveness downstream of the slot on both suction side and pressure side is rather high and it reaches almost 1.0 for about 8% axial chord of the vane surface on average in high blowing ratio cases.
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Key words:
- turbine vane /
- film cooling /
- coupling vortices /
- step-shaped slot /
- aerodynamic loss /
- cooling effctiveness /
- numerical simulation
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图 1 新型台阶缝冷却结构示意图
Figure 1. Schematic of proposed step-shaped slot film cooling configuration
图 3 台阶缝位置分布示意图
Figure 3. Schematic of distribution locations of step-shaped slot on the vane
图 6 台阶缝缝口局部流场示意图
Figure 6. Schematic of local flow field around step-shaped slot film cooling configuration
图 7 台阶缝对叶片表面压力系数的影响
Figure 7. Effect of coolant injection from step-shaped slot on blade pressure coefficient
图 8 台阶缝缝口附近叶片表面压力系数
Figure 8. Blade pressure coefficient around step-shaped slot film cooling configuration
图 9 叶片表面布置台阶缝对叶栅气动性能的影响
Figure 9. Effect of coolant injection from step-shaped slot on vane surface on cascade aerodynamic performance
图 10 叶片吸力面布置台阶缝时，叶高中部叶片表面上冷却效率随吹风比的变化
Figure 10. Variation of mid-span film cooling effectiveness of suction-side step-shaped slot with blowing ratio
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