摘要
针对冲击-气膜复合冷却结构,采用实验与数值方法,对比了基于圆形气膜孔的传统冲击、延伸冲击、小距离冲击、基于扇形气膜孔的传统冲击、延伸冲击5种复合冷却系统的耦合换热和流动特性。采用红外热成像技术,获得了5种复合冷却结构在吹风比分别为0.6、1.0、1.5时外壁面的综合冷却有效度,并通过数值计算进一步揭示了内部冷却的流动和换热特征。研究结果表明:在不产生额外气动损失的前提下,延伸冲击孔结构可提升内部冷却的换热系数,进而小幅度提升壁面的综合冷却有效度,幅度为1.2%~4.6%,但随着冷气量的增大综合冷却有效度提升幅度有所减小;减小冲击距离能够提升内部冲击换热效果,但不会对综合冷却有效度产生明显影响;采用扇形气膜孔可大幅度提升外部气膜冷却性能,且提升幅度大于采用延伸冲击内部改进结构的。相较于传统的圆形气膜孔-冲击复合冷却结构,在相同冷气量条件下,基于扇形孔的延伸冲击改进方案可将壁面的面平均综合冷却有效度提高7.6%~8.5%,并将系统的流量系数提升30%以上。
For the impingement-film composite cooling structure,the conjugate heat transfer and flow characteristics of five composite cooling systems,including traditional jet impingement,extended jet impingement,and small-distance jet impingement,in combination with cylindrical film holes and fan-shaped film holes,are compared by using experimental and computational approaches.Infrared thermography is used in experiments to obtain overall cooling effectiveness of the outer wall surface under three blowing ratios:0.6,1.0 and 1.5.The computational approach is used to further reveal the flow and heat exchange characteristics of internal cooling details.Results show that the extended jet impingement hole structure can enhance the internal heat transfer coefficient without generating additional aerodynamic losses,which in turn improves overall cooling effectiveness by a small amount,ranging from 1.2%to 4.6%,but the improvement decreased with the increase of the coolant mass flow rate,that reducing the impingement distance can enhance the internal impingement heat transfer performance,which had no significant effect on overall cooling effectiveness and that the use of fan-shaped film holes can significantly improve the external film cooling performance,and the enhancement was greater than that through the internal optimization structure using extended jet holes.Compared with the traditional composite cooling structure of cylindrical film holes combined with impingement,the extended jet impingement scheme based on fan-shaped holes can improve the area-averaged overall cooling effectiveness by 7.6%to 8.5%and improve discharge coefficient by more than 30%under the same amount of coolant.
作者
吴航
杨星
蔡海扬
刘钊
丰镇平
WU Hang;YANG Xing;CAI Haiyang;LIU Zhao;FENG Zhenping(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment,Xi’an 710049,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2024年第10期156-167,共12页
Journal of Xi'an Jiaotong University
基金
国家科技重大专项资助项目(2017-Ⅲ-0003-0027)。
关键词
耦合换热
延伸冲击
气膜冷却
综合冷却有效度
conjugate heat transfer
extended jet impingement
film cooling
overall cooling effectiveness
