带有初始横流的狭小空间内冲击冷却特性研究
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摘要
发动机涡轮叶片的冷却设计一直是现代高性能发动机研制中的关键和核心问题之一。随着现代加工工艺的进步,涡轮叶片内部的冷却结构日益复杂,出现了诸如小空间射流、多角度射流等特殊的冷却结构。本文利用数值模拟和实验研究的方法,对狭小空间内(冲击间距和冲击孔直径之比小于1)的多排冲击射流冷却开展了研究,重点分析了冲击雷诺数(3000 研究发现:在相同的冲击Rej数下,冲击间距较小(zn/d<1)时,冲击通道内的压力从上游到下游逐渐降低,这种上、下游之间的压差导致前、后排冲击孔的流量分配不均,即前排孔流量大于后排孔流量。沿流向方向,冲击射流在冲击通道滞止区上游方向会形成一个卷吸涡,随着上游冲击射流的不断加入,卷吸涡越来越小直至消失;垂直流向方向上,在冲击滞止区两侧会形成两个对称的漩涡。
计算和实验结果均表明:狭小空间内多排冲击射流在冲击靶面上游换热较差,下游换热较好;在其他条件相同时,冲击雷诺数越大换热效果越好;初始横流的加入削弱了前排射流的冲击冷却效果,并且使冲击孔正对的靶面低温区向下游方向偏移,且这种影响在大间距情况下表现得更加明显;冲击靶面上游的局部努塞尔数随冲击间距的减小而减小,而在靶面下游则随冲击间距的减小而增大;冲击孔排之间的间距的减小可以提高整个靶面的换热效果。
综合计算和实验分析:狭小空间多排射流冲击冷却特性受到流动参数和几何参数的共同影响,且影响规律与常规间距不完全相同,在实际工程应用中应综合考虑以获得理想的冷却效果。
The cooling system design of the gas turbine has been always the most important part of the advanced engine research. With the improvement of the modern manufacture techniques, the cooling structure becomes more complex, such as impingement in narrow spaces and in multi-angles. The numerical simulation and experiment were conducted to investigate the flow and heat transfer characteristics of impingement cooling structure in narrow spaces, which the ratio of the channel height to the diameter of impinging hole ( z n/d ) is smaller than 1. Some influential parameters were considered, such as jet Reynolds number (3000< Re j <10000), nozzle-to -plate distance (0.6< z n/d <2.0), initial cross-flow (0< Gc /G j<0.3) and jet-to-jet distance (2< xn /d <6).
Firstly, the flow field indicates that: there is an obvious pressure difference between the upstream and downstream region of jet-flow channel, which results in the unevenness of mass-flow quantum. The interaction of the multi jet streams leads to the formation of complex vortical structures that govern heat removal from the impinging surface. In the section along with the outflow direction, there is only one vortex upstream the stagnation region and it becomes smaller even disappered near the outlet. The vortex couple exists in the vertical plane of jet flow channel.
Then, local Nusselt numbers are evaluated on the specified lines located on the surface. The heat transfer on the upstream impinging target plate is better than downstream areas under the condition of narrow spaces. The heat transfer enhances clearly with the increase of the jet Reynolds number. Because of the initial cross-flow, the local Nusselt numbers decrease and do not show the secondary maxima at all. The cross-flow also pulls off the stagnation point downstream and the influent is significant in the regular nozzle-target distance. Changing jet-to-jet distance significantly affects the heat transfer process near the surface. Specifically, increasing the jet-to-jet distance can improve the heat transfer coefficient.
As a conclusion from the simulation and experiment results, the flow and heat transfer characteristics of jet array impingement in narrow spaces are determined by parameters both flowing and geometrical, which is not as the same as in regular impinging spaces. So it must be considered comprehensively in order to obtain the ideal cooling effect.
计算和实验结果均表明:狭小空间内多排冲击射流在冲击靶面上游换热较差,下游换热较好;在其他条件相同时,冲击雷诺数越大换热效果越好;初始横流的加入削弱了前排射流的冲击冷却效果,并且使冲击孔正对的靶面低温区向下游方向偏移,且这种影响在大间距情况下表现得更加明显;冲击靶面上游的局部努塞尔数随冲击间距的减小而减小,而在靶面下游则随冲击间距的减小而增大;冲击孔排之间的间距的减小可以提高整个靶面的换热效果。
综合计算和实验分析:狭小空间多排射流冲击冷却特性受到流动参数和几何参数的共同影响,且影响规律与常规间距不完全相同,在实际工程应用中应综合考虑以获得理想的冷却效果。
The cooling system design of the gas turbine has been always the most important part of the advanced engine research. With the improvement of the modern manufacture techniques, the cooling structure becomes more complex, such as impingement in narrow spaces and in multi-angles. The numerical simulation and experiment were conducted to investigate the flow and heat transfer characteristics of impingement cooling structure in narrow spaces, which the ratio of the channel height to the diameter of impinging hole ( z n/d ) is smaller than 1. Some influential parameters were considered, such as jet Reynolds number (3000< Re j <10000), nozzle-to -plate distance (0.6< z n/d <2.0), initial cross-flow (0< Gc /G j<0.3) and jet-to-jet distance (2< xn /d <6).
Firstly, the flow field indicates that: there is an obvious pressure difference between the upstream and downstream region of jet-flow channel, which results in the unevenness of mass-flow quantum. The interaction of the multi jet streams leads to the formation of complex vortical structures that govern heat removal from the impinging surface. In the section along with the outflow direction, there is only one vortex upstream the stagnation region and it becomes smaller even disappered near the outlet. The vortex couple exists in the vertical plane of jet flow channel.
Then, local Nusselt numbers are evaluated on the specified lines located on the surface. The heat transfer on the upstream impinging target plate is better than downstream areas under the condition of narrow spaces. The heat transfer enhances clearly with the increase of the jet Reynolds number. Because of the initial cross-flow, the local Nusselt numbers decrease and do not show the secondary maxima at all. The cross-flow also pulls off the stagnation point downstream and the influent is significant in the regular nozzle-target distance. Changing jet-to-jet distance significantly affects the heat transfer process near the surface. Specifically, increasing the jet-to-jet distance can improve the heat transfer coefficient.
As a conclusion from the simulation and experiment results, the flow and heat transfer characteristics of jet array impingement in narrow spaces are determined by parameters both flowing and geometrical, which is not as the same as in regular impinging spaces. So it must be considered comprehensively in order to obtain the ideal cooling effect.
引文
[1].陈光.航空发动机发展综述[J].航空制造技术,2000,6:24~27.
[2].何小民,常海萍.高推重比发动机热端部件的技术途径与战略决策[J].航空科学技术,1999,99(6):32~34.
[3].胡晓煜.国外典型的军用航空发动机技术发展计划[R].中国航空工业发展研究中心航空技术所,2008.
[4].倪萌,朱惠人,裘云,等.航空发动机涡轮叶片冷却技术综述[J].燃气轮机技术, 2005,18(4):25~33.
[5].刘大响,陈光.航空发动机-飞机的心脏[M].北京,航空工业出版社,2003.
[6].毛军逵.铸冷叶片内部冷却结构优化涉及研究,博士后出站报告[D] .2005.12.
[7].毛军逵,刘震雄,郭文.小间距单孔冲击凸面靶板流场结构实验[J].航空动力学报,2007, 22(10):1599–1603.
[8].刘震雄,毛军逵,郭文,等.双层壳型冲击/气膜复合冷却效果的实验研究[J].航空动力学报,2007,22(2):216-221.
[9].毛军逵,刘震雄,郭文.小间距冲击凹柱面流场特性实验[J].航空动力学报,2008,29(2):143–148.
[10]. Osama M. A. Al-aqal. Heat Transfer Distributions on the Walls of a Narrow Channel with Jet Impingement and Cross Flow[D], University of Pittsburgh, 1999.
[11]. E. Baydar, Y. Ozmen. An experimental investigation on flow structures of confined and unconfined impinging air jets[J]. Heat Mass Transfer Vol.42, No.4, pp.338-46.
[12]. L. B. Y. Aldabbagh, I. Sezai1, A. A. Mohamad. Three-Dimensional Investigation of a Laminar Impinging Square Jet Interaction With Cross-Flow[J]. Journal of Heat Transfer, Vol. 125,pp.243-249.
[13]. Bunker, R.S., Metzger, D.E. Local Heat Transfer in Internally Cooled Turbine Airfoil Leading Edge Regions - Part 1: Impingement Cooling without Film Coolant Extraction[J]. Journal of Turbomachinery, Vol.112, No.3, pp.451-458.
[14]. Viskanta, R. Heat Transfer to Impinging Isothermal Gas and Flame Jets[J]. Experimental Thermal and Fluid Science, 1993, Vol.6, pp,111~134.
[15]. R. J. Goldstein, A. I. Behbanhani. Impingement of a Circular Jet With and Without Crossflow[J]. Int. J. Heat Transfer, 1982, Vol.25, No.9, pp1377~1382.
[16]. E. M. Sparrow, R. J. Goldstein and M. A. Rouf. Effect of Nozzle. Surface Separation Distance onImpingement Heat Transfer for Clossflow[J]. Transactions of the ASME Journal of Engineering for Power, 1975, PP528~533.
[17]. J. P. Bouchez, R. J. Goldstein. Impingement Cooling from a circular Jet in a Cross Flow[J]. Int. J. Heat Mass Transfer, 1975, Vol.18, pp718~730.
[18]. L. W. Florschuetz, D. E. Metzger. Heat Transfer Characteristics for Jet Array Impingement with Initial Crossflow[J]. ASME, 83-GT-28.
[19]. L. W. Florschuetz, D. E. Metzger, Streamwise Flow and Heat Transfer Distributions for Jet Array Impingement with Crossflow[J]. ASME, 81-GT-77.
[20]. L. W. Florschuetz, Y. Isoda. Flow Distribution and Discharge Coefficient Effects for Jet Array Impingement with Initial Crossflow[J]. ASME, 82-GT-156.
[21].孔满昭,刘海涌,刘松龄,等.有错排射流冲击的短通道流场研究[J].航空动力学报,2006,21(1):66-72.
[22]. D. E. Metzger, L. W. Florschuetz. Heat Transfer Characteristics for Inline and Staggered Arrays of Circular Jets with Crossflow of Spent Air[J]. ASME Journal of Heat Transfer, Vol.101, pp.526-531.
[23].常海萍,张大林,韩东,等.有初始横流的冲击壁面强化的换热特性实验研究[J].航空动力学报,1996, 11(3): 269-272.
[24]. Chang Haiping, Zhang Dalin, Zhang Jingyu,etal. Impingement Heat Transfer from Rib Roughened Surface within Arrays of Circular Jet[J]. ASME 97-GT-331,1997.
[25]. Chang Haiping, Zhang Dalin. The Effect of the Relative Position of the Jet Hole to the Ribs. International Gas Turbine & Aero-engine Congress & Exhibition. Orlando, Florida ,1997.
[26].白云峰,常海萍,毛军逵,等.孔和粗糙肋相对位置对冲击冷却影响的数值研究.南京航空航天大学第六届学术会议.
[27].张净玉,常海萍.冲击粗糙壁面复合冷却实验研究[J].航空动力学报,2001年10月,16(4):386-389.
[28].张净玉.冲击粗糙表面复合冷却参数优化研究,硕士学位论文[D].南京:南京航空航天大学,1998.
[29].李永康,张靖周,谭晓茗,等.阵列射流冲击冷却局部对流换热特性的数值计算与试验验证[J].工程热物理学报,2004, 5.
[30].朱自强.应用计算流体力学[M].北京:北京航空航天大学出版社,1998.
[31].王福军.计算流体动力学分析[M].北京:清华大学出版社,2004.
[32]. Yakhot V, Orzag S A. Renormalization Group Analysis of Turbulence[R]. Basic Theory J ScientCompute, 1986, 1(1):3~51.
[33]. Ronald S. Bunker. Latticework(vortex) Cooling Effectiveness[A], Proceedings of ASME Expo2004, 2004, GT2004-54157.
[34]. FLUENT User's Guide[M].Fluent Inc., Lebanon, NH,1999.
[35].吴海玲,陈听宽.应用不同紊流模型对二维横向射流传热数值模拟研究[J].西安交通大学学报, 2001, 35(9):903~907.
[36].梁德旺.流体力学基础[M].北京:航空工业出版社,1998.
[37].阎畅.带出流及横流通道内斜冲击射流换热特性研究,博士学位论文[D].西安:西北工业大学, 2007.
[38].涡街流量计说明书.
[39]. NI使用说明.
[40].李鑫.狭小受限空间内冲击/稀疏气膜复合冷却特性研究,硕士学位论文[D].南京:南京航空航天大学,2009.
[41]. HLD-PBF-Ⅲ型导热系数测量仪使用说明书.
[42].陶云刚.测量误差与数据处理[M].南京:南京航空航天大学出版社,1996.
[43].高魁明.热工测量仪表[M].北京:冶金工业出版社,1985.
[2].何小民,常海萍.高推重比发动机热端部件的技术途径与战略决策[J].航空科学技术,1999,99(6):32~34.
[3].胡晓煜.国外典型的军用航空发动机技术发展计划[R].中国航空工业发展研究中心航空技术所,2008.
[4].倪萌,朱惠人,裘云,等.航空发动机涡轮叶片冷却技术综述[J].燃气轮机技术, 2005,18(4):25~33.
[5].刘大响,陈光.航空发动机-飞机的心脏[M].北京,航空工业出版社,2003.
[6].毛军逵.铸冷叶片内部冷却结构优化涉及研究,博士后出站报告[D] .2005.12.
[7].毛军逵,刘震雄,郭文.小间距单孔冲击凸面靶板流场结构实验[J].航空动力学报,2007, 22(10):1599–1603.
[8].刘震雄,毛军逵,郭文,等.双层壳型冲击/气膜复合冷却效果的实验研究[J].航空动力学报,2007,22(2):216-221.
[9].毛军逵,刘震雄,郭文.小间距冲击凹柱面流场特性实验[J].航空动力学报,2008,29(2):143–148.
[10]. Osama M. A. Al-aqal. Heat Transfer Distributions on the Walls of a Narrow Channel with Jet Impingement and Cross Flow[D], University of Pittsburgh, 1999.
[11]. E. Baydar, Y. Ozmen. An experimental investigation on flow structures of confined and unconfined impinging air jets[J]. Heat Mass Transfer Vol.42, No.4, pp.338-46.
[12]. L. B. Y. Aldabbagh, I. Sezai1, A. A. Mohamad. Three-Dimensional Investigation of a Laminar Impinging Square Jet Interaction With Cross-Flow[J]. Journal of Heat Transfer, Vol. 125,pp.243-249.
[13]. Bunker, R.S., Metzger, D.E. Local Heat Transfer in Internally Cooled Turbine Airfoil Leading Edge Regions - Part 1: Impingement Cooling without Film Coolant Extraction[J]. Journal of Turbomachinery, Vol.112, No.3, pp.451-458.
[14]. Viskanta, R. Heat Transfer to Impinging Isothermal Gas and Flame Jets[J]. Experimental Thermal and Fluid Science, 1993, Vol.6, pp,111~134.
[15]. R. J. Goldstein, A. I. Behbanhani. Impingement of a Circular Jet With and Without Crossflow[J]. Int. J. Heat Transfer, 1982, Vol.25, No.9, pp1377~1382.
[16]. E. M. Sparrow, R. J. Goldstein and M. A. Rouf. Effect of Nozzle. Surface Separation Distance onImpingement Heat Transfer for Clossflow[J]. Transactions of the ASME Journal of Engineering for Power, 1975, PP528~533.
[17]. J. P. Bouchez, R. J. Goldstein. Impingement Cooling from a circular Jet in a Cross Flow[J]. Int. J. Heat Mass Transfer, 1975, Vol.18, pp718~730.
[18]. L. W. Florschuetz, D. E. Metzger. Heat Transfer Characteristics for Jet Array Impingement with Initial Crossflow[J]. ASME, 83-GT-28.
[19]. L. W. Florschuetz, D. E. Metzger, Streamwise Flow and Heat Transfer Distributions for Jet Array Impingement with Crossflow[J]. ASME, 81-GT-77.
[20]. L. W. Florschuetz, Y. Isoda. Flow Distribution and Discharge Coefficient Effects for Jet Array Impingement with Initial Crossflow[J]. ASME, 82-GT-156.
[21].孔满昭,刘海涌,刘松龄,等.有错排射流冲击的短通道流场研究[J].航空动力学报,2006,21(1):66-72.
[22]. D. E. Metzger, L. W. Florschuetz. Heat Transfer Characteristics for Inline and Staggered Arrays of Circular Jets with Crossflow of Spent Air[J]. ASME Journal of Heat Transfer, Vol.101, pp.526-531.
[23].常海萍,张大林,韩东,等.有初始横流的冲击壁面强化的换热特性实验研究[J].航空动力学报,1996, 11(3): 269-272.
[24]. Chang Haiping, Zhang Dalin, Zhang Jingyu,etal. Impingement Heat Transfer from Rib Roughened Surface within Arrays of Circular Jet[J]. ASME 97-GT-331,1997.
[25]. Chang Haiping, Zhang Dalin. The Effect of the Relative Position of the Jet Hole to the Ribs. International Gas Turbine & Aero-engine Congress & Exhibition. Orlando, Florida ,1997.
[26].白云峰,常海萍,毛军逵,等.孔和粗糙肋相对位置对冲击冷却影响的数值研究.南京航空航天大学第六届学术会议.
[27].张净玉,常海萍.冲击粗糙壁面复合冷却实验研究[J].航空动力学报,2001年10月,16(4):386-389.
[28].张净玉.冲击粗糙表面复合冷却参数优化研究,硕士学位论文[D].南京:南京航空航天大学,1998.
[29].李永康,张靖周,谭晓茗,等.阵列射流冲击冷却局部对流换热特性的数值计算与试验验证[J].工程热物理学报,2004, 5.
[30].朱自强.应用计算流体力学[M].北京:北京航空航天大学出版社,1998.
[31].王福军.计算流体动力学分析[M].北京:清华大学出版社,2004.
[32]. Yakhot V, Orzag S A. Renormalization Group Analysis of Turbulence[R]. Basic Theory J ScientCompute, 1986, 1(1):3~51.
[33]. Ronald S. Bunker. Latticework(vortex) Cooling Effectiveness[A], Proceedings of ASME Expo2004, 2004, GT2004-54157.
[34]. FLUENT User's Guide[M].Fluent Inc., Lebanon, NH,1999.
[35].吴海玲,陈听宽.应用不同紊流模型对二维横向射流传热数值模拟研究[J].西安交通大学学报, 2001, 35(9):903~907.
[36].梁德旺.流体力学基础[M].北京:航空工业出版社,1998.
[37].阎畅.带出流及横流通道内斜冲击射流换热特性研究,博士学位论文[D].西安:西北工业大学, 2007.
[38].涡街流量计说明书.
[39]. NI使用说明.
[40].李鑫.狭小受限空间内冲击/稀疏气膜复合冷却特性研究,硕士学位论文[D].南京:南京航空航天大学,2009.
[41]. HLD-PBF-Ⅲ型导热系数测量仪使用说明书.
[42].陶云刚.测量误差与数据处理[M].南京:南京航空航天大学出版社,1996.
[43].高魁明.热工测量仪表[M].北京:冶金工业出版社,1985.