冷气预旋诱导涡系重构气膜冷却机理研究
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摘要
为了揭示不同进气腔配置诱导涡系重构对气膜冷却效果的影响,在圆柱形气膜孔的基础上研究了三种不同冷气腔结构以产生不同的进气预旋气膜冷却流动结构,并对三种冷气腔在吹风比分别为0.5、1.0、1.5、2.0的条件下进行了对比研究。结果表明:在低吹风比时,冷却气体出射动量小,三种进气方式的气膜冷却效率相当。随着吹风比的增加,进气预旋气膜冷却的优势逐渐显著。在吹风比为2.0时,原始进气冷却流体出射动量大且分布均匀,形成了强肾形涡,气膜冷却效率最低;第一种进气射流在孔上游形成一低动量区,该区域冷气与高温主流相互作用后绕开高动量区冷气射流后贴附壁面,在下游冷却效果明显;第二种进气冷却流体以单向旋涡的结构喷出,在下游形成一侧旋涡"压"着另一侧旋涡的流动形式,使被压旋涡中冷气更好地贴附壁面,射流侧向速度大,扩大了射流展向覆盖区域。相对于原始进气,第一种进气和第二种进气的平均绝热气膜效率,在吹风比为1.0时,分别提高了约10%和25%,在吹风比为1.5时,分别提高了约50%和550%。
In order to reveal the influence of the vortex reconstruction which is induced by swirling coolant flow on film cooling effectiveness, three different kinds of coolant chamber configuration based on the cylindrical hole are selected to develop the swirling flow structure of coolant, and the comparative investigations have been carried out to study the effect of different coolant chambers at blowing ratios ranging from 0.5 to 2.0. The results show that the coolant jet momentum is small at low blowing ratio, and the difference of the film cooling effectiveness of three kinds of coolant chamber configuration is little, but the advantage of swirling inflow coolant film cooling becomes obviously with the increase of blowing ratio. When the blowing ratio is 2.0, the jet momentum with original coolant chamber configuration is large and uniform, which leads to the lowest cooling effectiveness due to the formation of a strong kidney vortex. The first coolant chamber configuration has a low jet momentum region at upstream of the film hole, the coolant in this region interacts with high temperature mainstream and bypasses the large jet momentum coolant to attach cooling surface at downstream, the cooling effect is obvious at downstream. The second coolant chamber configuration is sprayed with the structure of unidirectional vortex, which forms a vortex pressing on other vortex, making the coolant in pressed vortex attach surface better. The coolant laterally velocity is large, producing the best coverage and the best film cooling effectiveness. The average film cooling effectiveness of the first and second coolant chamber configuration are larger than original by about 10% and 25%,respectively(M=1.0), or 50% and 550%(M=1.5).
In order to reveal the influence of the vortex reconstruction which is induced by swirling coolant flow on film cooling effectiveness, three different kinds of coolant chamber configuration based on the cylindrical hole are selected to develop the swirling flow structure of coolant, and the comparative investigations have been carried out to study the effect of different coolant chambers at blowing ratios ranging from 0.5 to 2.0. The results show that the coolant jet momentum is small at low blowing ratio, and the difference of the film cooling effectiveness of three kinds of coolant chamber configuration is little, but the advantage of swirling inflow coolant film cooling becomes obviously with the increase of blowing ratio. When the blowing ratio is 2.0, the jet momentum with original coolant chamber configuration is large and uniform, which leads to the lowest cooling effectiveness due to the formation of a strong kidney vortex. The first coolant chamber configuration has a low jet momentum region at upstream of the film hole, the coolant in this region interacts with high temperature mainstream and bypasses the large jet momentum coolant to attach cooling surface at downstream, the cooling effect is obvious at downstream. The second coolant chamber configuration is sprayed with the structure of unidirectional vortex, which forms a vortex pressing on other vortex, making the coolant in pressed vortex attach surface better. The coolant laterally velocity is large, producing the best coverage and the best film cooling effectiveness. The average film cooling effectiveness of the first and second coolant chamber configuration are larger than original by about 10% and 25%,respectively(M=1.0), or 50% and 550%(M=1.5).
引文
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[9]徐虹艳,张靖周,姚玉.涡轮叶片非对称扇形气膜孔冷却特性数值研究[J].机械工程学报,2011,47(18):152-157.XU Hongyan,ZHANG Jingzhou,YAO Yu.Numerical investigation on film cooling performance of turbine blade with asymmetrical fan-shaped holes[J].Journal of Mechanical Engineering,2011,47(18):152-157.
[10]杨成凤,张靖周,陈利强.前缘凸脊倾斜气膜冷却效果[J].机械工程学报,2009,45(9):312-316.YANG Chengfeng,ZHANG Jingzhou,CHEN Liqiang.Film cooling effectiveness of declining holes with tabs-ridged[J].Journal of Mechanical Engineering,2009,45(9):312-316.
[11]KUSTERER K,BOHN D,SUGIMOTO T,et al.Doublejet ejection of cooling air for improved film cooling[J].Journal of Turbomachinery,2000,122(1):133-121.
[12]KUSTERER K,ELYAS A,BOHN D,et al.A parametric study on the influence of the lateral ejection angle of doublejet holes on the film cooling effectiveness for high blowing ratios[C]//Proceedings of ASME Turbo Expo,Florida:International Gas Turbine Institute,2009,GT2009-59321.
[13]MARC J E,JUBRAN B A.A numerical study on improving large angle film cooling performance through the use of sister holes[J].Numerical Heat Transfer Applications,2009,55(7):634-653.
[14]SINHA A K,BOGARD D G,CRAWFORD M E.Film cooling effectiveness downstream of a single row of holes with variable density ratio[J].Journal of Turbomachinery,1991,113(3):442-449.
[2]曹玉璋,陶智,徐国强.航空发动机传热学[M].北京:北京航空航天大学出版社,2005.CAO Yuzhang,TAO Zhi,XU Guoqiang.Aero engine heat transfer[M].Beijing:Beihang University press,2005.
[3]GOLDSTEIN R J,ECKERT E R G,BURGGRAF F.Effects of hole geometry and density on three-dimensional film cooling[J].International Journal of Heat and Mass Transfer,1974,17(5):595-607.
[4]LEYLEK J H,ZERKLE R D.Discrete jet film cooling:a comparison of computational results with experiments[J].Journal of Turbomachinery,1994,116(3):358-368.
[5]李佳.燃气轮机透平气膜冷却机理的试验与理论研究[D].北京:清华大学,2011.LI Jia.Experimental and theoretical research on gas turbine film cooling[D].Beijing:Tsinghua University,2011.
[6]朱惠人,许都纯,刘松龄.气膜孔形状对排孔下游冷却效率的影响[J].航空学报,2004,23(1):75-78.ZHU Huiren,XU Duchun,LIU Songling.Effect of hole shape on film cooling effectiveness[J].Acta Aeronautica Et Astronautica Sinica,2004,23(1):75-78.
[7]戴萍,林枫.不同孔形气膜冷却效率的数值模拟[J].中国电机工程学报,2010(14):102-108.DAI Ping,LIN Feng.Numerical simulation on film cooling effectiveness for different shaped holes[J].Proceedings of the CSEE,2010(14):102-108.
[8]OKITA Y,NISHIURA M.Film effectiveness performance of an arrowhead-shaped film-cooling hole geometry[J].Journal of Turbomachinery,2007,129(2):331-339.
[9]徐虹艳,张靖周,姚玉.涡轮叶片非对称扇形气膜孔冷却特性数值研究[J].机械工程学报,2011,47(18):152-157.XU Hongyan,ZHANG Jingzhou,YAO Yu.Numerical investigation on film cooling performance of turbine blade with asymmetrical fan-shaped holes[J].Journal of Mechanical Engineering,2011,47(18):152-157.
[10]杨成凤,张靖周,陈利强.前缘凸脊倾斜气膜冷却效果[J].机械工程学报,2009,45(9):312-316.YANG Chengfeng,ZHANG Jingzhou,CHEN Liqiang.Film cooling effectiveness of declining holes with tabs-ridged[J].Journal of Mechanical Engineering,2009,45(9):312-316.
[11]KUSTERER K,BOHN D,SUGIMOTO T,et al.Doublejet ejection of cooling air for improved film cooling[J].Journal of Turbomachinery,2000,122(1):133-121.
[12]KUSTERER K,ELYAS A,BOHN D,et al.A parametric study on the influence of the lateral ejection angle of doublejet holes on the film cooling effectiveness for high blowing ratios[C]//Proceedings of ASME Turbo Expo,Florida:International Gas Turbine Institute,2009,GT2009-59321.
[13]MARC J E,JUBRAN B A.A numerical study on improving large angle film cooling performance through the use of sister holes[J].Numerical Heat Transfer Applications,2009,55(7):634-653.
[14]SINHA A K,BOGARD D G,CRAWFORD M E.Film cooling effectiveness downstream of a single row of holes with variable density ratio[J].Journal of Turbomachinery,1991,113(3):442-449.