Effect of crossflow on internal heat transfer of impingement-swirl-film cooling for leading edge of turbine blade
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摘要:
针对真实涡轮叶片前缘非对称的冲击-旋流-气膜冷却通道,在定冲击进口雷诺数和定总流量两种情况下,通过改变横流比,数值研究了主动横流入流对冷却通道换热效果的影响规律;并拟合获得了两组工况下的努塞尔数无量纲关系式。结果表明:在冲击进口雷诺数不变的情况下,增加横流比会增强冲击靶面的整体换热能力;当雷诺数为
20000 时,横流比为2获得的努塞尔数比无横流工况时增加了25.8%。在总流量不变的情况下,增加横流比会减弱冲击靶面的整体换热能力;当总流量为0.0236 kg/s时,横流比为2获得的努塞尔数比无横流工况时降低了43.3%。非对称的冲击-旋流-气膜前缘冷却通道内的冷却效果主要由冲击射流决定,相比较而言横流对流冷却影响较小。通过拟合获得的两种情况的努塞尔数关系式,对涡轮叶片前缘非对称结构的研究和优化具有指导意义。Abstract:The asymmetric impingement-swirl-film cooling channel of a realistic turbine blade leading edge was studied. Under two conditions—constant impingement inlet Reynolds number and constant total flow rate, the effect of active crossflow on the heat transfer performance of the cooling channel was numerically investigated by varying the crossflow ratio. Dimensionless Nusselt number correlations at both operating conditions were derived through curve fitting. The results indicated that, under a constant Reynolds number of the impingement inlet, increasing the crossflow ratio enhanced the overall heat transfer performance of the impingement target surface. Specifically, when the Reynolds number was
20000 , a crossflow ratio of 2 led to a 25.8% increase in the Nusselt number compared with the no-crossflow case. Conversely, under a constant total flow rate, increasing the crossflow ratio reduced the overall heat transfer performance of the impingement target surface. When the total flow rate was0.0236 kg/s, a crossflow ratio of 2 resulted in a 43.3% reduction in the Nusselt number compared with the no-crossflow case. The findings demonstrated that the cooling performance in the asymmetric impingement-swirl-film cooling channel was primarily governed by the impinging jet, while the effect of crossflow convection was relatively minor. The fitted Nusselt number correlations for both scenarios can provide a valuable guidance for the design and optimization of asymmetric leading-edge cooling structures in turbine blades.-
Key words:
- leading edge /
- composite cooling /
- swirl cooling /
- crossflow /
- dimensionless correlation
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表 1 结构几何参数
Table 1. Geometrical parameters of structure
mm 几何参数 数值 冲击孔直径 d 10 气膜孔直径 d′ 3 冲击隔板和吸力面延长线交点与
吸力面下端点距离 l173 压力面和吸力面延长线交点与
压力面上端点距离 l254 冲击隔板-吸力面交接面曲率半径和
冲击隔板-吸力面交接面曲率半径 r15 叶片前缘曲率半径 r2 12.5 冲击孔偏移距离 e 15 气膜孔间距 s 15 冲击隔板与前缘3排气膜孔进口中心点
垂直距离 i1, i2, i320, 25, 30 表 2 不同雷诺数下具体工况
Table 2. Specific conditions under different Reynolds numbers
Re m2/(kg/s) m2/m1 104 0.00787 1,2,3,4 2×104 0.0157 0.5,1,1.5,2 3×104 0.0236 0.33,0.67,1,1.33 4×104 0.0315 0.25,0.5,0.75,1 表 3 不同流量下具体工况
Table 3. Specific working conditions under different flow rates
m/(kg/s) 0.0157 0.0236 0.03148 m2/m1 0.05/0.1/0.33/0.5/0.75/1/1.5/2/2.5/3 -
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