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为了研究不同孔型对平板气膜冷却的影响,针对圆形,扇形,水滴形,收敛缝形四种气膜出流孔型的流动和传热特性进行了数值模拟。研究结果表明,圆形孔、扇形孔和水滴形孔气膜出口下游出现从中心向上抬升的反向旋转涡对,将主流燃气卷吸进来;收敛缝形孔在侧向的扩张型面使得气膜出流在展向的覆盖更为均匀,这有效地阻止了高温气体的侵入;在相同吹风比下,收敛缝形孔在气膜出口附近区域的平均绝热冷却效率则明显要高于其余三种孔,随着吹风比的增大,这种差距越发明显;孔型对对流换热系数增强比的影响区域仅局限在邻近气膜孔出口大约7倍气膜孔径的范围内。
In order to study the influence of different hole types on the cooling of flat film, the numerical simulation of the flow and heat transfer characteristics of four film outlet holes with circular, fan-shaped, teardrop-shaped and convergent seam shapes was carried out. The results show that there is reverse swirling vortex pair rising upwards from the center downstream of the outlet of the round hole, the fan hole and the droplet-shaped film, and the mainstream gas is entrained in the downstream of the gas outlet; The outflow of film flow is more uniform in the span direction, which effectively prevents the intrusion of hot gases. The average adiabatic cooling efficiency of convergent slit holes in the vicinity of the gas film outlet is significantly higher than that of the other three With the increase of blowing ratio, the difference is more obvious. The influence of pore type on convective heat transfer enhancement ratio is only limited to about 7 times of film pore diameter near the exit of film hole.