克努森数对气膜冷却流动换热相似特性的影响

Effect of Knudsen number on similar characteristics of film cooling flow and heat transfer

数值模拟研究克努森数Kn对不同尺度气膜冷却流动换热相似特性的影响,选取孔径为0.3,3,10mm平板单排圆柱形气膜孔模型,计算得到模型在Kn不同与相同条件下冷却效率和孔流量系数.结果表明:Kn相同时,小孔与大孔模型流动换热特性相似,冷却效率及流量系数均吻合很好;Kn不同时,两模型流动换热特性存在一定差异,冷却效率及流量系数吻合较差.因此为在气膜冷却相似放大研究中得到准确的相似结果,需要保证小孔及大孔模型的Kn相同.

The effect of Knudsen number Kn on the similar characteristics between different scale film cooling flow and heat transfer was numerically studied. Single-row plate cylindrical hole film cooling models with aperture of 0.3, 3, 10 mm were seleeted. Cooling effectiveness and discharge coefficient of models under condition of different Kn and the same Kn were calculated. Results show that small and large hole models have similar flow and heat transfer characteristics under the same value of Kn, resulting in little differences between cooling effectiveness and discharge coefficient. When Kn varies, the flow and heat transfer characteristics of these two models are different, bringing about different cooling effectiveness and discharge coefficients. Therefore it is necessary to make sure that small and large hole models should have the same Kn in similar amplification experiment of film cooling.