带肋横流进气方式下气膜孔的流阻特性与机理研究

Flow Resistance Characteristics and Mechanism of Film

关键词:  气膜冷却  带肋横流  流量系数  吹风比  横流雷诺数

Key words:  Film cooling  Ribbed crossflow  Discharge coefficient  Blowing ratio  Crossflow Reynolds number

摘要:

为了更好地研究内冷结构对外部气膜孔流阻特性的影响，在带肋横流进气方式下，实验测得不同横流雷诺数(Rec=1×105，5×104)和吹风比(M=0.5，1，2)下的圆柱型气膜孔流量系数，并结合数值模拟分析了横流雷诺数、45°肋结构和吹风比对气膜孔流阻特性的影响机理。结果表明:带肋横流进气方式下，横流引起的孔内旋流是流量系数减小的主要因素，肋引起的进口堵塞使得流量系数进一步减小；横流雷诺数相同时，流量系数随吹风比的增大而增大，当吹风比增大至M=2时，流量系数趋于一定值；小吹风比(M=0.5 ~ 1)时，横流雷诺数越大流量系数越小，随吹风比的增大(M=1 ~ 2)，横流雷诺数对流量系数的影响逐渐减小。

Abstract:

In order to find out the effects of internal cooling structures on outer film cooling performance，experimental measurements and numerical simulations have been carried out to investigate the flow resistance characteristics and mechanism of cylindrical holes with coolant crossflow in ribbed channel over a series of crossflow Reynolds number(Rec=1×105，5×104) and blowing ratio(M=0.5，1，2). The results show that the swirl flow in the hole caused by the crossflow is the main reason for the decrease of discharge coefficient. Flow blockage at hole entrance caused by the rib can further reduce the discharge coefficient. Under the same crossflow Reynolds number，the discharge coefficient increases with the blowing ratio and approaches to a constant value when the blowing ratio increases to 2. Under low blowing ratios(M=0.5 ~ 1)，the discharge coefficient decreases with the increase of crossflow Reynolds number. However，the effects of crossflow Reynolds number on the discharge coefficient become smaller with the increase of blowing ratio(M=1 ~ 2).