燃气轮机动叶气膜冷却效果评价方法的改进
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摘要
为了更全面地对气膜冷却叶片的整体冷却效果进行评价,以气膜冷却效率评价指标为出发点,引入平均冷却效率和不均匀度系数2个新的评价指标,应用FLUENT软件对某型大功率燃气轮机第一级动叶在不同工况下进行了数值模拟计算,用新定义的评价指标对叶片冷却效果进行了分析。研究结果表明,冷却效率评价指标对单孔或放大的模型能够有效地表达气膜冷却效果的好坏,但其局限性是不能定量地反映气膜冷却效果的均匀性,从而使得气膜冷却效果整体评价不全面。通过平均气膜冷却效率值和不均匀系数值分布规律发现,同一吹风比条件下,随着孔间距的增大,冷气覆盖程度变差,平均气膜冷却效率值降低,且不均匀系数不断增大,叶片压力面冷气分布越不均匀;受孔排冷气的动量叠加效应影响,叶片后缘冷气覆盖程度好,冷却效率明显高于前缘;在相同孔间距条件下,随着吹风比的增大,叶片压力面平均气膜冷却效率增大,不均匀系数值不断减小,叶片压力面冷却气体分布越均匀。
In order to get the overall evaluation of film cooling effect,taking the evaluation index of film cooling efficiency as the starting point,the other two kinds of evaluation indicators as average film cooling efficiency and cooling non-uniformity coefficient were introduced.The computational fluid dynamics software FLUENT was used to simulate the complex flow process of the first stage of a certain type of high power gas turbine under the different working conditions.The results of the study show that the cooling efficiency can effectively express the film cooling effect under the circumstances of single hole or enlarged model,but it had limitation in quantitatively representing the homogeneity of film cooling effect which make against the overall evaluation of film cooling effect.Through the average film cooling efficiency value and the distribution of cooling non-uniformity coefficient values,it was found that under the same blowing ratio,with the increase of the hole spacing,the coverage of cooling air becomes worse and the average film cooling efficiency was de-creased.Meanwhile,the non-uniformity coefficient was increased and the distribution of air pressure on the pressure surface of blade became more uniform.The effect of momentum superposition on the cold air of the hole expulsion is better than that of the leading edge,and the cooling margin of the trailing edge is better than that of the leading edge.With the increase of the blowing ratio,the average film cooling efficiency of the pressure surface of the blade was increased,and the non-uniformity coefficient was decreased and the cooling gas distribution of the blade pressure surface became more uniform.
In order to get the overall evaluation of film cooling effect,taking the evaluation index of film cooling efficiency as the starting point,the other two kinds of evaluation indicators as average film cooling efficiency and cooling non-uniformity coefficient were introduced.The computational fluid dynamics software FLUENT was used to simulate the complex flow process of the first stage of a certain type of high power gas turbine under the different working conditions.The results of the study show that the cooling efficiency can effectively express the film cooling effect under the circumstances of single hole or enlarged model,but it had limitation in quantitatively representing the homogeneity of film cooling effect which make against the overall evaluation of film cooling effect.Through the average film cooling efficiency value and the distribution of cooling non-uniformity coefficient values,it was found that under the same blowing ratio,with the increase of the hole spacing,the coverage of cooling air becomes worse and the average film cooling efficiency was de-creased.Meanwhile,the non-uniformity coefficient was increased and the distribution of air pressure on the pressure surface of blade became more uniform.The effect of momentum superposition on the cold air of the hole expulsion is better than that of the leading edge,and the cooling margin of the trailing edge is better than that of the leading edge.With the increase of the blowing ratio,the average film cooling efficiency of the pressure surface of the blade was increased,and the non-uniformity coefficient was decreased and the cooling gas distribution of the blade pressure surface became more uniform.
引文
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[6]张玲,修栋波,汪山入.化工燃气轮机动叶全表面气膜冷却影响的数值模拟[J].化工机械,2016(2):186-193.ZHANG Ling,XIU Dong-bo,WANG Shan-ru.Numerical simulation of unsteady wakes’effect on film cooling of rotor bade surface[J].Chemical Engineering and Machinery,2016(2):186-193.
[7]林晓春,刘建军.透平叶栅气膜冷却损失分析[J].工程热物理学报,2016(8):1627-1634.LIN Xiao-chun,LIU Jian-jun.The loss analysis of film cooling on turbine vane cascade[J].Journal of Engineering Thermophysics,2016(8):1627-1634.
[8]戴萍,林枫.孔间距对缩放槽缝孔气膜冷却效率的影响[J].汽轮机技术,2010(3):191-194,214.DAI Ping,LIN Feng.Influence of hole pitch on film cooling effectiveness from converging slot-hole[J].Turbine Technology,2010(3):191-194,214.
[9]戴萍.气膜孔几何结构对涡轮叶片气膜冷却的影响研究[D].哈尔滨:哈尔滨工程大学,2010.DAI Ping.Study on the influence of film hole configuration on turbine blade film cooling[D].Harbin:Harbin Engineering University,2010.
[10]于飞龙,上官博,李园园,等.重型燃气轮机透平第一级动叶复合冷却数值研究[J].中国电机工程学报,2016(1):179-186.YU Fei-long,SHANGGUANG Bo,LI Yuan-yuan,et al.Numerical investigation on compound cooling effect of the heavy-duty gas turbine first stage blade[J].Proceedings of the CSEE,2016(1):179-186.
[11]沈菁菁.燃气轮机叶片气膜冷却数值模拟[D].上海:上海发电设备成套设计研究院,2014.SHENG Qing-qing.Numerical simulation of filming cooling on gas turbine blade[D].Shanghai:Shanghai Power Equipment Research Institute,2014.
[12]骆剑霞.涡轮叶片内冷结构对外部气膜冷却特性的影响研究[D].西安:西北工业大学,2015.LUO Jian-xia.Research of external film cooling performance of turbine blade with different internal cooling structures[D].Xi’an:Northwestern Polytechnical University,2015.
[2]刘聪,朱惠人,付仲议,等.涡轮动叶压/吸力面气膜孔冷却特性实验研究[J].推进技术,2016(3):511-519.LIU Cong,ZHU Hui-ren,FU Zhong-yi,et al.Experimental study of film cooling characteristics on pressure and suction side in a turbine blade[J].Journal of Propulsion Technology,2016(3):511-519.
[3]常艳,杨卫华,张靖周.突片形状对气膜冷却效率的影响[J].南京航空航天大学学报,2016(3):317-325.CHANG Yan,YANG Wei-hua,ZHANG Jing-zhou.Effects of tab shaps on film cooling effectiveness[J].Journal of Nanjing University of Aeronautics and Astronautics,2016(3):317-325.
[4]Dring R P,Blair M F,Joslyn H D.An experimental investigation of film cooling on a turbine rotor blade[J].Journal of Engineering for Power,1980,102(1):81-87.
[5]李少华,李知骏,王梅丽,等.旋转对复合角度气膜冷却叶片的数值模拟[J].汽轮机技术,2011(3):164-166.LI Shao-hua,LI Zhi-jun,WANG Mei-li,et al.Numerical simulation study on the effect of rotation on film cooling of blades with compound angle holes[J].Turbine Technology,2011(3):164-166.
[6]张玲,修栋波,汪山入.化工燃气轮机动叶全表面气膜冷却影响的数值模拟[J].化工机械,2016(2):186-193.ZHANG Ling,XIU Dong-bo,WANG Shan-ru.Numerical simulation of unsteady wakes’effect on film cooling of rotor bade surface[J].Chemical Engineering and Machinery,2016(2):186-193.
[7]林晓春,刘建军.透平叶栅气膜冷却损失分析[J].工程热物理学报,2016(8):1627-1634.LIN Xiao-chun,LIU Jian-jun.The loss analysis of film cooling on turbine vane cascade[J].Journal of Engineering Thermophysics,2016(8):1627-1634.
[8]戴萍,林枫.孔间距对缩放槽缝孔气膜冷却效率的影响[J].汽轮机技术,2010(3):191-194,214.DAI Ping,LIN Feng.Influence of hole pitch on film cooling effectiveness from converging slot-hole[J].Turbine Technology,2010(3):191-194,214.
[9]戴萍.气膜孔几何结构对涡轮叶片气膜冷却的影响研究[D].哈尔滨:哈尔滨工程大学,2010.DAI Ping.Study on the influence of film hole configuration on turbine blade film cooling[D].Harbin:Harbin Engineering University,2010.
[10]于飞龙,上官博,李园园,等.重型燃气轮机透平第一级动叶复合冷却数值研究[J].中国电机工程学报,2016(1):179-186.YU Fei-long,SHANGGUANG Bo,LI Yuan-yuan,et al.Numerical investigation on compound cooling effect of the heavy-duty gas turbine first stage blade[J].Proceedings of the CSEE,2016(1):179-186.
[11]沈菁菁.燃气轮机叶片气膜冷却数值模拟[D].上海:上海发电设备成套设计研究院,2014.SHENG Qing-qing.Numerical simulation of filming cooling on gas turbine blade[D].Shanghai:Shanghai Power Equipment Research Institute,2014.
[12]骆剑霞.涡轮叶片内冷结构对外部气膜冷却特性的影响研究[D].西安:西北工业大学,2015.LUO Jian-xia.Research of external film cooling performance of turbine blade with different internal cooling structures[D].Xi’an:Northwestern Polytechnical University,2015.