非定常尾迹对动叶气膜冷却影响的数值分析
摘要
气膜冷却作为一种有效的保护手段被越来越多的应用在燃气轮机叶片上。由于燃气透平内部流场的复杂性，使得气膜冷却效果受到许多因素不同程度的影响，其中一个主要因素是来自上游静叶的尾迹传播。静叶尾迹导致自由流产生周期性变化的不稳定速度场和温度场，进而影响下游动叶气膜冷却效果，因此研究非定常尾迹对动叶气膜冷却效果的影响具有重要的意义。
本文采用SST k-ω紊流模型，在SIMPLE算法基础上，利用有限体积法对控制方程进行离散。首先研究了不同吹风比、不同转速时非定常尾迹对动叶前缘气膜冷却和叶片传热以及周围流场的影响，得到了各工况下的冷却射流流线图、气膜冷却效率分布图、努赛尔数分布图和流场瞬时湍动能图，经过比较分析发现：吹风比的增大将改变出流状况，使射流发生旋转并偏向叶顶方向流动，提高转速将加剧射流的旋转，甚至改变出流方向；气膜孔附近的冷却效率随着吹风比的增大而增大，但吸力面孔下游的冷却效率有所降低，转速的增大加速了射流与主流的扰动，提高了气膜孔周围的冷却效率，但在n=2000rpm时，第三排孔附近的冷却效果减弱；吹风比增大使得叶片表面整体换热增强，但转速对换热的影响比较复杂，M=1.0时压力面的换热较好，n=500rpm时吸力面的换热较好；吹风比的增大导致气膜孔附近流场的紊流加剧，转速增大则导致动静间叶栅通道的紊流急剧，气动损失较大。
由于上游尾迹以一定的频率扫过动叶前缘，导致流场和叶片周围的物理参数发生周期性的变化。通过研究一个周期内不同时刻动叶周围流场的瞬时等温图、湍动能图、马赫数图和传热系数图，得到如下结论：0.5T（T为周期）时刻到1.0T时刻期间气膜温度较低且覆盖较广，0.9T时刻的冷却效果最为理想；整个周期里湍动能、马赫数和传热系数的变化不是很大，湍动能较大值集中在第一排射流附近和动叶尾缘处，在0.7T时刻，动静叶栅间通道的马赫数较大，动叶压力面侧射流孔附近的换热系数较大，吸力面侧中部的换热系数较高，但在尾缘处有所下降。
The film cooling gas as a kind of protection means were widely used in gasturbine blade. Because of the complexity of the internal flow field of the gas turbine,many factors influence the effect of gas film-cooling, one major factor is the trail ofstatic leaves from spread. Static leaves make the freedom trail produce not stable flowvelocity and temperature fields periodically, and then to effect film-cooling of blade.,so the unsteady wake to move leaves film cooling effect of the gas has importantsignificance.
This paper adopts SST k-ω turbulence model based on SIMPLE algorithm anddiscretizes the control equation using finite volume method. Firstly, the influence ofunsteady wake on film-cooling of blade, heat transfer and flow field around of bladehave been studied, got the path chart of cooling, gas jet film cooling efficiency map,Nusselt number distribution and flow field instantaneous turbulent kinetic energyfigure, through comparison analysis, we found that：The increasing of blow ratio willchange the flow condition, make jet occurred to the blade tip rotation and direction,improving speed will heighten jet spinning, and even change the flow direction；Withthe increasing of blow ratio, film-cooling efficiency nearby jet hole increases, butfilm-cooling efficiency of downstream film hole reduces, the speed increaseaccelerated mixing of jet and the mainstream, improve the gas film hole around thecooling efficiency, but in n=2000rpm, the area around of the third row-cooling holeeffect weakens, blow ratio increasing makes the surface heat transfer enhancementoverall, but the effect of speed on heat exchange is more complicated, heat transfer ofpressure surface is better when M=1.0, and suction surface's heat transfer is betterwhen n=500rpm；The increasing of blow ratio enhances the turbulence of flow fieldnearby film hole, speed increasing leads to turbulence aggravate in the channelbetween blade sharp, and pneumatic loss bigger.
Upstream wake swept blade at a certain frequency, so physical parameters offlow field and blade surface change periodically. Through the study of isothermalfigure、turbulent kinetic energy instantaneous map、Mach number and heat transfercoefficient graph figure in different time of a period, got a conclusion：During thetime from0.5T to1.0T, gas film cooling temperature is lower and covers a wide area,cooling effect at0.9T is best；The changing of turbulent kinetic energy、 the Machnumber and the heat transfer coefficient is not great in the whole periodic, turbulentkinetic energy larger value is in the first row of concentrated near the jet and leavestrailing edge place of blade, the Mach number is larger at0.7T time between thechannel rotating blade and static blade, the heat transfer coefficient near jet hole ofpressure side is higher, and the heat coefficient at the middle suction face is bigger,but reduced in the trailing edge.
本文采用SST k-ω紊流模型，在SIMPLE算法基础上，利用有限体积法对控制方程进行离散。首先研究了不同吹风比、不同转速时非定常尾迹对动叶前缘气膜冷却和叶片传热以及周围流场的影响，得到了各工况下的冷却射流流线图、气膜冷却效率分布图、努赛尔数分布图和流场瞬时湍动能图，经过比较分析发现：吹风比的增大将改变出流状况，使射流发生旋转并偏向叶顶方向流动，提高转速将加剧射流的旋转，甚至改变出流方向；气膜孔附近的冷却效率随着吹风比的增大而增大，但吸力面孔下游的冷却效率有所降低，转速的增大加速了射流与主流的扰动，提高了气膜孔周围的冷却效率，但在n=2000rpm时，第三排孔附近的冷却效果减弱；吹风比增大使得叶片表面整体换热增强，但转速对换热的影响比较复杂，M=1.0时压力面的换热较好，n=500rpm时吸力面的换热较好；吹风比的增大导致气膜孔附近流场的紊流加剧，转速增大则导致动静间叶栅通道的紊流急剧，气动损失较大。
由于上游尾迹以一定的频率扫过动叶前缘，导致流场和叶片周围的物理参数发生周期性的变化。通过研究一个周期内不同时刻动叶周围流场的瞬时等温图、湍动能图、马赫数图和传热系数图，得到如下结论：0.5T（T为周期）时刻到1.0T时刻期间气膜温度较低且覆盖较广，0.9T时刻的冷却效果最为理想；整个周期里湍动能、马赫数和传热系数的变化不是很大，湍动能较大值集中在第一排射流附近和动叶尾缘处，在0.7T时刻，动静叶栅间通道的马赫数较大，动叶压力面侧射流孔附近的换热系数较大，吸力面侧中部的换热系数较高，但在尾缘处有所下降。
The film cooling gas as a kind of protection means were widely used in gasturbine blade. Because of the complexity of the internal flow field of the gas turbine,many factors influence the effect of gas film-cooling, one major factor is the trail ofstatic leaves from spread. Static leaves make the freedom trail produce not stable flowvelocity and temperature fields periodically, and then to effect film-cooling of blade.,so the unsteady wake to move leaves film cooling effect of the gas has importantsignificance.
This paper adopts SST k-ω turbulence model based on SIMPLE algorithm anddiscretizes the control equation using finite volume method. Firstly, the influence ofunsteady wake on film-cooling of blade, heat transfer and flow field around of bladehave been studied, got the path chart of cooling, gas jet film cooling efficiency map,Nusselt number distribution and flow field instantaneous turbulent kinetic energyfigure, through comparison analysis, we found that：The increasing of blow ratio willchange the flow condition, make jet occurred to the blade tip rotation and direction,improving speed will heighten jet spinning, and even change the flow direction；Withthe increasing of blow ratio, film-cooling efficiency nearby jet hole increases, butfilm-cooling efficiency of downstream film hole reduces, the speed increaseaccelerated mixing of jet and the mainstream, improve the gas film hole around thecooling efficiency, but in n=2000rpm, the area around of the third row-cooling holeeffect weakens, blow ratio increasing makes the surface heat transfer enhancementoverall, but the effect of speed on heat exchange is more complicated, heat transfer ofpressure surface is better when M=1.0, and suction surface's heat transfer is betterwhen n=500rpm；The increasing of blow ratio enhances the turbulence of flow fieldnearby film hole, speed increasing leads to turbulence aggravate in the channelbetween blade sharp, and pneumatic loss bigger.
Upstream wake swept blade at a certain frequency, so physical parameters offlow field and blade surface change periodically. Through the study of isothermalfigure、turbulent kinetic energy instantaneous map、Mach number and heat transfercoefficient graph figure in different time of a period, got a conclusion：During thetime from0.5T to1.0T, gas film cooling temperature is lower and covers a wide area,cooling effect at0.9T is best；The changing of turbulent kinetic energy、 the Machnumber and the heat transfer coefficient is not great in the whole periodic, turbulentkinetic energy larger value is in the first row of concentrated near the jet and leavestrailing edge place of blade, the Mach number is larger at0.7T time between thechannel rotating blade and static blade, the heat transfer coefficient near jet hole ofpressure side is higher, and the heat coefficient at the middle suction face is bigger,but reduced in the trailing edge.
引文
[1]韩介勤，桑地普·杜达，斯瑞纳斯·艾卡德．燃气轮机传热和冷却技术．第一版．程代京，谢永慧译．西安：西安交通大学出版社．2005．2~4
[2]葛绍岩，刘登瀛，徐靖中等．气膜冷却,第一版．北京：科学出版社．1985．203~206
[3] K Wieghardt．Hot-Air Discharge for De-icing，AAF Translation，ReportNo.FTS-919-Re，1946：1~44
[4] A. B. Mehendale，S. V. Kkad， J. C. Han．Main Stream Turbulence Effect onFilm Effectiveness and Heat Transfer Coefficient of a Gas Turbine Blade withAir and CO2Film Injection. International Journal of Heat and Mass Transfer，1994，37：2707-2714
[5] H. W. Jiang， J. C. Han． Effect of Film Hole Row Location on FilmEffectivenesson a Gas Turbine Blade．ASME，Journal of Heat Trandfer，1996，118：327-333
[6] Jan Dittmar，Achmed Schulz, and Sigmar Witting．Adiabatic Effectiveness andHeat Transfer Coefficient of Shaped Film Cooling Holes on a Scaled GuideVane Pressure Side Model．International Journal of Rotating Machinery，2004，10(5)：345-354
[7]李广超，朱惠人，廖乃冰等．气动参数对前缘气膜冷却效率影响的实验[J]．航空动力学报，2010，25(8)：1738-1745
[8]范宜龙，朱惠人，李永红等.逆压力梯度下几何参数对气膜冷却效率的影响[J]．航空动力学报，2010，25(8)：1738-1745
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[11]李志强.异型孔阵对气膜冷却效果的数值研究[J].热科学与技术，2010，9(2)：126-132
[12]杨凡，曹辉，郑洪涛等.涡轮静叶前缘气膜冷却数值模拟[J].汽轮机技术，2006，48(4):269-320
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[14]马兰，朱惠人，屈展，等.涡轮动叶表面气膜冷却换热实验研究[J].机械设计与制造，2005，(8)：133-135
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[22] Dring R P，Blair M F，Joslyn H D. An experimental investigation of filmcooling on a turbine blade[J]. ASME Journal of Engineering for Power，1980，102：81-87
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[2]葛绍岩，刘登瀛，徐靖中等．气膜冷却,第一版．北京：科学出版社．1985．203~206
[3] K Wieghardt．Hot-Air Discharge for De-icing，AAF Translation，ReportNo.FTS-919-Re，1946：1~44
[4] A. B. Mehendale，S. V. Kkad， J. C. Han．Main Stream Turbulence Effect onFilm Effectiveness and Heat Transfer Coefficient of a Gas Turbine Blade withAir and CO2Film Injection. International Journal of Heat and Mass Transfer，1994，37：2707-2714
[5] H. W. Jiang， J. C. Han． Effect of Film Hole Row Location on FilmEffectivenesson a Gas Turbine Blade．ASME，Journal of Heat Trandfer，1996，118：327-333
[6] Jan Dittmar，Achmed Schulz, and Sigmar Witting．Adiabatic Effectiveness andHeat Transfer Coefficient of Shaped Film Cooling Holes on a Scaled GuideVane Pressure Side Model．International Journal of Rotating Machinery，2004，10(5)：345-354
[7]李广超，朱惠人，廖乃冰等．气动参数对前缘气膜冷却效率影响的实验[J]．航空动力学报，2010，25(8)：1738-1745
[8]范宜龙，朱惠人，李永红等.逆压力梯度下几何参数对气膜冷却效率的影响[J]．航空动力学报，2010，25(8)：1738-1745
[9]向安定，刘松龄，朱惠人.涡轮工作叶片表面气膜冷却效率的实验研究[J]．推进技术，2004，25(1)：39-43
[10]姚玉，张靖周，何飞等.涡轮叶片吸力面气膜冷却效率的数值研究[J].航空动力学报，2010，25(6)：1245-1250
[11]李志强.异型孔阵对气膜冷却效果的数值研究[J].热科学与技术，2010，9(2)：126-132
[12]杨凡，曹辉，郑洪涛等.涡轮静叶前缘气膜冷却数值模拟[J].汽轮机技术，2006，48(4):269-320
[13]韩振兴，末永杰，刘石.吹风比对气膜冷却效率影响的实验研究[J].航空学报，2004，25(6)：551-555
[14]马兰，朱惠人，屈展，等.涡轮动叶表面气膜冷却换热实验研究[J].机械设计与制造，2005，(8)：133-135
[15]刘高文，刘松龄.喷射角对涡轮叶栅端壁气膜冷却传热的影响[J].推进技术，2002，23(6)：496-512
[16]向安定，罗小强，朱惠人等.涡轮叶片表面气膜冷却的传热实验研究[J].航空动力学报，2002，17(5):577-581
[17] Ammari, H. D., Hay.N., and Lampard, D. The Effect of Density Ratio on HeatTransfer Coefficient From a Film-Cooled Flat Plate. ASME Journal ofTurbo-machinery，1990，112：444-450
[18]杨帆，朱惠人，李广超.叶片前缘气膜冷却数值模拟[J].机械设计与制造，2007，(4)：23-25
[19]王虎齐，陈党慧，康顺.涡轮叶片前缘气膜冷却的数值模拟[J].动力工程，2007，27(1)：6-10
[20]颜培刚，王松涛.涡轮叶栅前缘气膜冷却对气动参数影响的数值研究[J].推进技术，2004，25(1)：44-47
[21] Abhari R S, Epstein A H. An experimental study of film cooling in a rotatingtransonic turbine[J]. ASME Journal of Turbomachinery，1994，116：63-70
[22] Dring R P，Blair M F，Joslyn H D. An experimental investigation of filmcooling on a turbine blade[J]. ASME Journal of Engineering for Power，1980，102：81-87
[23] Takeishi K，Mat suura M， Aoki S，et al. Film cooling on a gas turbine rotorblade[J]. ASME Journal of Turbomachinery，1991，112：488-496
[24] Pat rick Y, Ding S T, Tao Z. Numerical investigation of the rotation on the filmcooling over a flat surface[C]. N Y1001625990，United States: AmericanSociety of Mechanical Engineers,2005:GT2005268553,3:527-536
[25]杨晓军，陶智，丁水汀等.旋转对气膜冷却覆盖区域的影响[J].北京航空航天大学学报，2007，33(12):1383-1386
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