多形态狭缝型槽道结构的叶片前缘气膜冷却特性研究

Investigation of Film Cooling Characteristics at a Blade Leading Edge with Multiple Slotted-Channel Configurations

摘要

针对重型燃气轮机透平叶片前缘离散气膜孔冷却效率有限、冷气易脱离壁面的问题，提出了一种狭缝型槽道气膜冷却结构。采用基于雷诺时均方程的数值模拟方法，研究了该结构及其下缘几何构型（横槽、锯齿槽、圆弧槽）以及0.7～1.5区间吹风比对气膜冷却流动换热特性的影响机理。结果表明，与传统离散孔相比，狭缝型槽道有效抑制了气膜脱离，在冷气出口下游约3倍孔径范围内形成稳定连续的近壁气膜，平均气膜冷却效率提升达77.7%。吹风比敏感性分析结果显示，当吹风比增至1.5时，尽管冷气出口温度分布均匀性下降，但近壁冷气流量占比升高，总体冷却效率仍有增强。下缘几何对调控流动分离具有关键作用：锯齿槽可通过诱导二次流增强横向扩散，获得最佳的气膜附壁性，使冷却效率相比横槽进一步提高27.3%；圆弧槽则通过降低局部阻力使冷却效率相比横槽提升了19.8%。该研究结果可为重型燃气轮机透平叶片前缘高效冷却结构的仿生设计提供理论参考。

Abstract

To address the limited cooling effectiveness of conventional discrete film-cooling holes at the leading edge of heavy-duty gas turbine blades and the tendency of the coolant to detach from the wall,a slotted-channel film-cooling structure is proposed.Numerical simulations based on the Reynolds-averaged Navier-Stokes (RANS) equations are performed to investigate the effects of the structure,its lower-edge geometries (transverse,serrated,and arc-shaped grooves),and blowing ratios ranging from 0.7 to 1.5 on film-cooling flow and heat-transfer characteristics.It is shown that,compared with conventional discrete holes,film detachment is effectively suppressed by the slotted-channel structure,and a stable and continuous near-wall film is formed within approximately three hole diameters downstream of the coolant outlet,with the average film-cooling effectiveness increased by up to 77.7%.Blowing-ratio sensitivity analysis shows that when the blowing ratio increases to 1.5,although the uniformity of the temperature distribution at the coolant outlet decreases,the proportion of near-wall coolant flow increases,and the overall cooling effectiveness is still enhanced.Flow separation is significantly affected by the lower-edge geometry.Lateral diffusion is enhanced by secondary flows induced by the serrated groove,and the best film attachment is achieved,with the cooling effectiveness further increased by 27.3% compared with the transverse groove.For the arc-shaped groove,the cooling effectiveness is increased by 19.8% compared with the transverse groove through a reduction in local flow resistance.A theoretical reference for the biomimetic design of high efficiency leading-edge cooling structures for heavy-duty gas turbine blades is provided by these results.

关键词

流动换热 / 气膜冷却 / 叶片前缘 / 狭缝型槽

Key words

flow and heat transfer / film cooling / blade leading edge / slotted-channel

参考文献

[1] Attalla M,Salem M. Heat transfer from a flat surface to an inclined impinging jet[J]. Heat and Mass Transfer, 2014,50(7):915-922.

[2] Tepe A Ü,Uysal Ü,Yetişken Y,et al. Jet impingement cooling on a rib—roughened surface using extended jet holes[J]. Applied Thermal Engineering, 2020,178:115601.

[3] Bunker R S. A review of shaped hole turbine film—cooling technology[J]. Journal of Heat Transfer, 2005,127(4):441-453.

[4] Chen Lingling,Brakmann R G A,Weigand B,et al. Detailed investigation of staggered jet impingement array cooling performance with cubic micro pin fin roughened target plate[J]. Applied Thermal Engineering, 2020,171:115095.

[5] Xie Gongnan,Liu Jian,Ligrani P M,et al. Flow structure and heat transfer in a square passage with offset mid—truncated ribs[J]. International Journal of Heat and Mass Transfer, 2014,71:44-56.

[6] Singh P,Ravi B V,Ekkad S V. Experimental and numerical study of heat transfer due to developing flow in a two—pass rib roughened square duct[J]. International Journal of Heat and Mass Transfer, 2016,102:1245-1256.

[7] Du Wei,Luo Lei,Wang Songtao,et al. Enhanced heat transfer in a labyrinth channels with ribs of different shape[J]. International Journal of Numerical Methods for Heat & Fluid Flow, 2019,30(2):724-741.

[8] Yousefi A,Nejat A,Sabour M H. Ribbed channel heat transfer enhancement of an internally cooled turbine vane using cooling conjugate heat transfer simulation[J]. Thermal Science and Engineering Progress, 2020,19:100641.

[9] Xie Gongnan,Song Yidan,Asadi M,et al. Optimization of pin—fins for a heat exchanger by entropy generation minimization and constructal law[J]. Journal of Heat Transfer, 2015,137(6):061901.

[10] Goldstein R J. Film cooling[M]//Irvine T F,Hartnett J P.Advances in Heat Transfer.Amsterdam,Netherlands:Elsevier,1971:321-379.

[11] 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.

[12] Okita Y,Nishiura M. Film effectiveness performance of an arrowhead—shaped film—cooling hole geometry[J]. Journal of Turbomachinery, 2007,129(2):331-339.

[13] Lu Yiping,Faucheaux D,Ekkad S V. Film cooling measurements for novel hole configurations[C]//ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS,NEMS,and Electronic Systems.New York,USA:ASME,2005:59-66.

[14] Lee H W,Joon Park J,Sik Lee J . Flow visualization and film cooling effectiveness measurements around shaped holes with compound angle orientations[J]. International Journal of Heat and Mass Transfer, 2002,45(1):145-156.

[15] Lee K D,Kim K Y. Performance evaluation of a novel film—cooling hole[J]. Journal of Heat Transfer, 2012,134(10):101702.

[16] Li Lin,Chen Cunliang,Ye Lin,et al. Experimental investigation on effects of cross—flow Reynolds number and blowing ratios to film cooling performance of the Y—shaped hole[J]. International Journal of Heat and Mass Transfer, 2021,179:121682.

[17] Yang Xing,Liu Zhao,Feng Zhenping. Numerical evaluation of novel shaped holes for enhancing film cooling performance[J]. Journal of Heat Transfer, 2015,137(7):071701.

[18] 杨晓军,张雪丽,常嘉文. 叶片前缘波纹形气膜孔不同参数冷却特性研究[J]. 热能动力工程, 2023,38(7):28-35.

[19] Yang Xiaojun,Zhang Xueli,Chang Jiawen. Study on cooling characteristics of different parameters of corrugated holes at the leading edge of blade[J]. Journal of Engineering for Thermal Energy and Power, 2023,38(7):28-35.

[20] Kim J H,Kim K Y. Film—cooling performance of converged—inlet hole shapes[J]. International Journal of Thermal Sciences, 2018,124:196-211.

[21] Bunker R S. Film cooling effectiveness due to discrete holes within a transverse surface slot[C]//ASME Turbo Expo 2002:Power for Land,Sea,and Air.New York,USA:ASME,2002:129-138.

[22] 章大海,陈秋炀,曾敏,等. 不同横槽结构对气膜冷却效率影响的数值研究[J]. 航空动力学报, 2008,23(4):611-616.

[23] Zhang Dahai,Chen Qiuyang,Zeng Min,et al. Numerical investigation on the effect of different transverse trench configurations on film cooling effectiveness[J]. Journal of Aerospace Power, 2008,23(4):611-616.

[24] 章大海,王振波,曲燕,等. 开槽气膜孔结构对气膜冷却和流动特性的影响[J]. 燃气轮机技术, 2010,23(4):27-32.

[25] Zhang Dahai,Wang Zhenbo,Qu Yan,et al. The influence of trenched film hole configurations on film cooling and flowing characteristics[J]. Gas Turbine Technology, 2010,23(4):27-32.

[26] 孙璐,章大海,曾敏,等. 开槽前扩孔及复合角对气膜冷却的影响[J]. 工程热物理学报, 2009,30(10):1723-1725.

[27] Sun Lu,Zhang Dahai,Zeng Min,et al. Effects of a trenched—hole,shaped hole and compound angle on film cooling[J]. Journal of Engineering Thermophysics, 2009,30(10):1723-1725.

[28] Kalghatgi P,Acharya S. Improved film cooling effectiveness with a round film cooling hole embedded in a contoured crater[J]. Journal of Turbomachinery, 2015,137(10):101006.

[29] 李广超,陈钰恺,刘永泉,等. 利用W型槽提高气膜冷却效率机理[J]. 推进技术, 2016,37(3):520-526.

[30] Li Guangchao,Chen Yukai,Liu Yongquan,et al. Mechanism on increasing film cooling effectiveness by W shape slots[J]. Journal of Propulsion Technology, 2016,37(3):520-526.

[31] Wei Jiansheng,Zhu Huiren,Liu Cunliang,et al. Experimental study on the film cooling characteristics of the cylindrical holes embedded in sine—wave shaped trench[C]//ASME Turbo Expo 2016:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2016:V05CT19A017.

[32] Zhang Bolun,Zhang Li,Zhu Huiren,et al. Numerical study on the influence of trench width on film cooling characteristics of double—wave trench[C]//ASME Turbo Expo 2017:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2017:V05AT12A008.

[33] Abdala A M M,Elwekeel F N M,Zheng Qun. Theoretical film cooling effectiveness investigation on C3X vane suction side with multi trench configuration[C]//Proceedings of the 1st International Conference on Mechanical Engineering and Material Science (MEMS 2012).Paris,French:Atlantis Press,2012:463-466.

[34] Albert J E,Bogard D G . Measurements of adiabatic film and overall cooling effectiveness on a turbine vane pressure side with a trench[J]. Journal of Turbomachinery, 2013,135(5):051007.

[35] Rao K V,Liu J S,Crites D C,et al. Enhanced film cooling effectiveness with surface trenches[C]//ASME Turbo Expo 2013:Turbine Technical Conference and Exposition.New York,USA:ASME,2013:V03BT13A017.

[36] He Wei,Deng Qinghua,Zhou Weilun,et al. Film cooling and aerodynamic performances of a turbine nozzle guide vane with trenched cooling holes[J]. Applied Thermal Engineering, 2019,150:150-163.

[37] Rocha P A C,Rocha H H B,Carneiro F O M,et al. A case study on the calibration of the k—ω SST (shear stress transport) turbulence model for small scale wind turbines designed with cambered and symmetrical airfoils[J]. Energy, 2016,97:144-150.

[38] Kim Y J,Kim S M. Influence of shaped injection holes on turbine blade leading edge film cooling[J]. International Journal of Heat and Mass Transfer, 2004,47(2):245-256.

基金资助

国家自然科学基金资助项目(52276037)