双出口孔射流气膜冷却换热特性数值模拟

为了优化气膜冷却结构,通过数值模拟研究了一种新型气膜孔(由两个圆柱孔组成的双出口孔)的气膜冷却换热特性。利用Fluent软件对N-S方程进行求解,湍流模型采用两方程realizable k-ε模型和增强壁面函数处理。重点研究了吹风比对气膜冷却换热系数、换热系数比和热流比的影响。结果表明,换热系数随吹风比增大而增大,随x/d增大而减小,气膜孔附近尤其明显。吹风比0.5和1.0时,换热系数比随x/d增大而减小;吹风比1.5和2.0时,换热系数比随x/d增大先减小后增大。在研究的吹风比范围,双出口孔射流气膜冷却起到了削减从燃气传入叶片热流的作用。吹风比从0.5增大到1.0,热流比减小;吹风比从1.0增大到2.0,热流比增大。热流比随x/d增大而增大,气膜冷却的冷却效果减小。

Numerical simulation of film cooling heat transfer with injection of double-outlet hole

In order to optimize the geometry of film cooling,the heat transfer performance of a novel hole with double-outlet injection was investigated by numerical simulation.The N-S equation was solved by Fluent.The realizable k-ε model and enhanced wall function were used.The emphasis is focused on the heat transfer coefficient ratio and heat flux ratio.The results show that the heat transfer coefficients increase with increasing blowing ratios and decrease with increasing x/d,especially near the hole.The heat transfer coefficient ratios increase with increasing x/d at the blowing ratios of 0.5 and 1.0.The heat transfer coefficient ratios increase firstly and then decrease with increasing x/d at the blowing ratios of 1.5 and 2.0.The film cooling with double outlets hole injection takes a role in reduction of the heat flux from the gas to the blade.The heat flux ratios decrease when the blowing ratios increase from 0.5 to 1.0 and increase when the blowing ratios increase from 1.0 to 2.0.The heat flux ratios increase with increasing x/d,resulting in decreasing film cooling performance.