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针对多层层板冷却、双层壁冷却等冷却技术,利用数值模拟分析了这些冷却结构形成的狭小冷却通道中,气膜孔附近的流动特性,重点研究了气膜孔流量系数Cd随吹风比M(0.5~2.0)、气膜孔雷诺数Re(5000~10000)以及冷却通道高度H和气膜孔直径D之比H/D(0.33~1.0)等参数的变化规律.数值计算中湍流模型为Realizablek-ε模型,近壁处采用非平衡壁面函数,利用SIMPLE算法和二阶迎风格式进行离散求解.计算结果表明:气膜孔流量系数随吹风比的增大而增大,在吹风比M小于1时,影响尤为明显.研究中同时发现在相同吹风比的条件下,Cd随着气膜孔雷诺数的增大而减小,但变化的幅度不大;在相同的气膜孔雷诺数下,Cd随着H/D的减小而降低,特别是当H/D小于0.75时,随着流体在进入气膜孔前逐步受到限制,Cd随着H/D的减小而快速降低.
According to the cooling technology of multi-layer plate cooling and double-wall cooling, the flow characteristics near the film hole in the narrow cooling channel formed by these cooling structures are analyzed by numerical simulation. The effects of film hole flow coefficient Cd with blowing ratio M (0.5-2.0), Reynolds number Re (5000-10000), and the ratio H / D (0.33-1.0) of the cooling channel height H and the diameter of the film hole D. The numerical results of the turbulence model Realizablek-ε model, the unbalanced wall function is adopted near the wall, and the SIMPLE method and the second-order upwind method are used to solve discretely.The results show that the film flow coefficient increases with the increase of blowing ratio, 1, the effect is particularly obvious.At the same time, we found that under the same blowing ratio, Cd decreases with the increase of Reynolds number of gas film pores, but the change range is not large. Under the same Reynolds number Cd decreased with the decrease of H / D. Especially when H / D was less than 0.75, Cd decreased rapidly with the decrease of H / D as the fluid was gradually restricted before entering the film pores.