双排孔顺-逆射流组合方式对气膜冷却的影响

Effects of Combination of Forward Jet and Backward Jet with Two Rows of Holes on Film Cooling

关键词:  气膜冷却  射流  逆向射流  数值模拟

Key words:  Film cooling  Jet  Backward injection  Numerical simulation

摘要:

为了挖掘逆向射流气膜冷却潜力，数值模拟研究了顺向射流和逆向射流不同组合方式的双排孔气膜冷却叠加特性。吹风比变化为0.3～1.4。结果表明，展向平均气膜冷却效率数值模拟结果与实验值偏差小于9%。逆向射流在气膜孔出口产生的回流涡强化了气膜展向扩散，吹风比越大，强化效果越明显。吹风比为1.4时，与顺向射流+顺向射流组合结构的叠加区气膜冷却效率相比，上游顺向射流+下游逆向射流组合结构展向平均气膜冷却效率提高17%～233%，面平均气膜冷却效率提高64%；逆向射流+逆向射流组合结构展向平均气膜冷却效率提高0～410%，面平均气膜冷却效率提高62%；上游逆向射流+下游顺向射流组合展向平均气膜冷却效率提高16%～70%，面平均气膜冷却效率提高44%。

Abstract:

In order to analyze the film cooling performance of backward injection， the film cooling superposition characteristics of two rows of holes with the different combinations of forward and backward injection were numerically simulated at blowing ratios from 0.3 to 1.4. Results show that the difference of the lateral averaged film effectiveness is less than 9% for the numerical and experimental data. The separation vortex generated at the outlet of the film hole strengthens the lateral diffusion of the coolant of the backward injection. The increased blowing ratio causes the more obvious enhancement effect. Compared with the structure combining the upstream forward and forward injections， the averaged film cooling effectiveness of the other three kinds of combinations is improved at blowing ratio of 1.4. The lateral averaged film effectiveness combining upstream forward and downstream injections increased by 17% to 233% depending on the different location and the surface averaged film cooling effectiveness increased by 64%. The lateral averaged film cooling effectiveness combining backward and backward injections increased by 0 to 410% and the surface averaged film cooling effectiveness increased by 62%. The lateral averaged film cooling effectiveness combining backward and forward injections increased by 16% to 70% and the surface averaged film cooling effectiveness increased by 44%.