利用小孔射流改善气膜冷却效率的数值研究

为了获得气膜孔下游放置一对射流小孔对气膜冷却效率的影响规律,采用数值模拟方法研究了不同吹风比下射流小孔出口位置尺寸不同时流动过程和冷却效率的分布情况,并与常规气膜孔冷却结构形式进行对比,以揭示小孔射流改善气膜冷却效率的作用机理.研究表明:在常规气膜孔下游开两个射流小孔后,两射流小孔分别产生一个较弱的与气膜孔反向涡对方向相反的反向涡对,反向涡对的相互作用减弱了气膜孔反向涡对的强度,使气膜的贴壁效果更好,提高了气膜孔的冷却效率.在各吹风比条件下,气膜孔下游有射流小孔时,冷却效率都有一定的提高,并且射流小孔间距较大时对两气膜孔中心线之间的横向平均冷却效率改善较大,吹风比较大时,效果更明显.

Numerical investigation on improvement of film cooling effectiveness with small coolant jets

To investigate the influence of small coolant jets on film cooling effectiveness,the distributions of the flow fields and cooling effectiveness with the small jets at different outlet placement under several blowing ratios were numerically studied.And the distributions were compared with the distributions of the baseline holes to reveal the good effects of the small coolant jets on the film cooling performance.The results show that,the new interaction between the weaker counter-rotating vortex pairs(CRVP) generated by the small jets and the CRVP generated by the main coolant jet weakens the mixing strength of the coolant jets with the hot cross flow,so the film effectiveness is higher with better coverage on the hot side under several blowing ratios.And the spanwise cooling effectiveness is improved significantly when the distance between the two small coolant jets is longer and the blowing ratio is higher.