平板冲击发散冷却流动与换热特性的数值模拟

Numerical Simulation for Flow and Heat Transfer Characteristics of Impingement/Effusion Cooling on a Flat Plane

采用ANSYS-CFX商用软件对模化平板冲击发散冷却结构中的流动与换热特性进行了数值模拟,对比了有、无固体域时冲击发散冷却的冷却效率,分析了不同吹风比时气体的流动结构、涡强度、综合冷却效率和流动效率的变化,分析了固体导热系数对冷却效率的影响。结果表明:冲击发散冷却同时具有冲击冷却和气膜冷却的优点,可以有效保护壁面;当吹风比增大时,冲击冷却的效果增强,肾型涡强度增大,气膜冷却效果减弱,但冲击冷却的影响优于气膜冷却,所以其综合冷却效率仍然提高了;气膜冷却部分有最大的局部压力损失系数,当吹风比增大时,总压力损失系数增大,流动效率下降;当固体导热系数增大时,冲击冷却的影响增大,综合冷却效率提高。该结果可为进一步冷却燃气轮机内工作部件提供参考。

Flow characteristics and heat transfer of impingement/effusion cooling on a flat plane were numerically analyzed by ANSYS-CFX software. The simulation for the working conditions with and without solid domain was carried out to find their influence on the cooling performance. The influence of solid thermal conductivity and effects of blowing ratio on the flow structure, vortex intensity, total cooling efficiency and flow efficiency were discussed. The results show that impingement/effusion cooling has advantages of both impingement and film cooling to protect the solid surface well. When blowing ratio becomes larger, the impingement is more effective, and the film cooling acts adversely. But the impingement cooling is more influential so the total cooling efficiency increases. The film cooling part has the largest local pressure loss coefficient, and total pressure loss coefficient increases with the increasing blowing ratio. When the solid thermal conductivity becomes larger, the impingement cooling is more influential and the total cooling effectiveness increases.