气膜-发散组合冷却结构换热特性的实验研究

Experimental Investigation on Heat Transfer Characteristicsof Film-Effusion Combined Cooling

关键词:  航空发动机  火焰筒冷却  气膜-发散组合冷却  绝热冷却效率  对流换热系数

Key words:  Aeroengine  Combustion cooling  Film-effusion cooling  Adiabatic cooling effectiveness  Convective heat transfer coefficient

摘要:

为了研究气膜-发散组合冷却结构的冷却特征，保证相同的开孔率，设计了三种不同发散孔排布形式的组合冷却结构，采用实验的方法对气动参数和几何参数对绝热冷却效率和对流换热系数的影响规律开展了研究。结果表明:绝热冷却效率和对流换热系数沿主流方向先逐渐降低，达到最低点后沿流动方向二者基本保持不变；在研究参数范围内，主流雷诺数和吹风比对绝热冷却效率的影响不大，但对组合冷却结构的对流换热系数影响较大，随着主流雷诺数和吹风比的增加，对流换热系数均呈现逐渐增大的趋势；针对三种发散孔排布形式的绝热冷却效率和对流换热系数，流向间距大的气膜发散冷却结构最高，流向间距居中的气膜发散冷却结构次之，流向间距最小的气膜发散冷却结构最低。

Abstract:

In order to study the cooling characteristics of film-effusion combination cooling structure， three kinds of test pieces of different effusion cooling holes arrangement but equivalent orifice area were designed. The effects of aerodynamic parameters and geometric parameters on the adiabatic cooling efficiency and the convective heat transfer coefficient were investigated experimentally. The experimental results show that the adiabatic cooling efficiency and convective heat transfer coefficient gradually decrease in the direction of mainstream， and reache the lowest point， then they remain unchanged. The main flow Reynolds number and the blowing ratio have no evident effect on the adiabatic cooling efficiency under research range of parameters， but the effect on convective coefficient is evident， that is increased gradually with the increase of main flow Reynolds number or blowing ratio. For the three test specimens， the adiabatic cooling efficiency and the convective coefficient of the cooling structure of the largest stream wise spacing are the largest， and followed by the cooling structure of medium stream wise spacing， and the minimum is the cooling structure of the minimum stream wise spacing.