针对具有气膜出流孔和针肋的双层壁冷却结构内冲击传热性能进行了试验和数值计算研究。试验采用瞬态液晶（TLC）热像技术，研究的靶板包括光滑靶板、针肋靶板以及带气膜出流孔的针肋靶板。冲击间距比为1.5，射流雷诺数范围为15 000~30 000。结果表明，针肋+气膜出流孔结构明显改善了下游区域横流的影响，明显提高了传热性能，靶板表面传热分布也更加均匀。相比于平板，当射流雷诺数为15 000时，针肋靶板和带气膜出流孔的针肋靶板端壁表面平均Nusselt数提升幅度最大，分别为6.3%和25.3%。针对双层壁冷却结构内射流冲击传热还开展了数值计算，通过采用SST （Shear Stress Transport）k-ω湍流模型计算分析获得了该双层壁冷却结构内的流动和传热特征。
Multiple-jet impingement heat transfer performance in a double-wall cooling structure with pin fins and film effusion holes has been studied experimentally and numerically. Transient Liquid Crystal (TLC) thermography experimental method was used to explore the heat transfer characteristics on three target plates:flat plate, pin fin plate and pin fin plate with effusion holes. The jet-to-plate spacing was fixed to 1.5, and the Reynolds number based on the jet diameter ranges from 15 000 to 30 000. The experimental results show that the pin fin and effusion holes structure reduces the strength of the cross flow in the downstream region, improves and uniforms the heat transfer on the whole target plate obviously. When Reynolds number equals 15 000, there is a highest improvement of averaged Nusselt number on the endwall. Compared with that of the flat plate, the averaged Nusselt number of the pin fin plate and pin fin + effusion holes plate increases by 6.3% and 25.3%. For the numerical method, SST (Shear Stress Transport) k-ω turbulence model was employed to get an understanding of the flow structure and heat transfer on the pin fin and effusion holes surfaces.
[1] HADA S, TSUKAGOSHI K, JUNICHIRO M. Test results of the world's first 1600℃ J-series gas turbines[J]. MHI Technical Review, 2012, 49(1):18-23.[2] LEE D H, SONG J, JO M C. The effects of nozzle diameter on impinging jet heat transfer and fluid flow[J]. Journal of Heat Transfer, 2004, 126(4):554-557.[3] KATTI V, PRABHU S V. Influence of spanwise pitch on local heat transfer distribution for in-line arrays of circular jets with spent air flow in two opposite directions[J]. Experimental Heat Transfer, 2009, 22(4):228-256.[4] DAILEY G M, CHAMBERS A C, GILLESPIE D R H, et al. The effect of initial cross flow on the cooling performance of a narrow impingement channel[J]. Journal of Heat Transfer, 2005, 127(4):358-365.[5] LI W H, LI X Y, REN J. Effect of Reynolds number, hole patterns and hole inclination on cooling performance of an impingement jet array:Part Ⅰ-Convective heat transfer results and optimization:GT2016-56205[R]. New York:ASME, 2016.[6] SHAN Y, ZHANG J Z, XIE G N. Convective heat transfer for multiple rows of impinging air jets with small jet-to-jet spacing in a semi-confined channel[J]. International Journal of Heat and Mass Transfer, 2015, 86:832-842.[7] CHANG H P, ZHANG D L, HUANG T P. Impingement heat transfer from rib roughened surface within arrays of circular jet:The effect of the relative position of the jet hole to the ribs:GT1997-331[R]. New York:ASME, 1997.[8] ANDREWS G, HUSSAIN R A A A, MKPADI M C. Enhanced impingement heat transfer:Comparison of co-flow and cross-flow with rib turbulators:IGTC-2003-075[R]. Tokyo:Gas Turbine Society of Japan, 2003.[9] ZHANG J Z, LI L G. High-resolution heat transfer coefficients measurement for jet impingement using thermochromic liquid crystals[J]. Chinese Journal of Aeronautics, 2001, 14(4):205-209.[10] XING Y, SPRING S, WEIGAND B. Experimental and numerical investigation of impingement heat transfer on a flat and micro-ribs roughened plate with different crossflow schemes[J]. International Journal of Thermal Sciences, 2011, 50(7):1293-1307.[11] DEVORE M A, PAAUWE C S. Turbine airfoil with improved cooling:7600966 B2[P]. 2009-10-13.[12] CHYU M K, SIW S H. Recent advances of internal cooling techniques for gas turbine airfoils[J]. Journal of Thermal Science and Engineering Applications,2013, 5(2):021008.[13] ZHANG J Z, XIE H, YANG C F. Numerical study of flow and heat transfer characteristics of impingement/effusion cooling[J]. Chinese Journal of Aeronautics, 2009, 22(4):343-348.[14] 郑杰,朱惠人.微尺度冲击冷却通道换热特性实验研究[J]. 推进技术, 2015, 36(1):82-88. ZHENG J, ZHU H R. Experimental investigation on jet impingement heat transfer for micro-channel[J]. Journal of Propulsion Technology, 2015, 36(1):82-88(in Chinese).[15] IRELAND P T, JONES T V. Liquid crystal measurements of heat transfer and surface shear stress[J]. Measurement Science and Technology, 2000, 11(7):969-986.[16] KLINE S J, MCCLINTOCK F A. Describing uncertainties in single-sample experiments[J]. Mechanical Engineering, 1953, 75(1):3-8.[17] KINGSLEY-ROWE J R, LOCK G D, OWEN J M. Transient heat transfer measurements using thermochromic liquid crystal:Lateral-conduction error[J]. International Journal of Heat and Fluid Flow, 2005, 26(2):256-263.[18] XING Y, SPRING S, WEIGAND B. Experimental and numerical investigation of heat transfer characteristics of inline and staggered arrays of impinging jets[J]. Journal of Heat Transfer, 2010, 132(9):092201.[19] ROACHE P J. Perspective:A method for uniform reporting of grid refinement studies[J]. Journal of Fluids Engineering, 1994, 116(3):405-413.[20] EI-GABRY L A, KAMINSKI D A. Experimental investigation of local heat transfer distribution on smooth and roughened surfaces under an array of angled impingement jets[J]. Journal of Turbomachinery, 2005, 127(3):532-544.[21] KERCHER D, TABAKOFF W. Heat transfer by a square array of round air jets impinging perpendicular to a flat surface including the effect of spent air[J]. Journal of Engineering for Power, 1970, 92(1):73-82.
CJA