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.
作者
李录平
唐学智
张浩
黄章俊
LI Lu-ping;TANG Xue-zhi;ZHANG Hao;HUANG Zhang-jun(School of Energy and Power Engineering？ Changsha University of Science and Technology？ Changsha 410114,China)
出处
《长沙理工大学学报（自然科学版）》
CAS
2018年第2期81-87,共7页
Journal of Changsha University of Science and Technology:Natural Science
基金
中国南方电网有限责任公司科技计划项目(K-GD2014-0583002-002)
关键词
燃气轮机
动叶片
气膜冷却
数值模拟
吹风比
气膜冷却效果评价
均匀性
gas turbine
moving blade
film cooling
numerical simulation
blowing ratio
film cooling effect evaluation
the homogeneity
