槽缝射流旋流比和密度比对涡轮端壁冷却和吸力面泛冷却性能的影响
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摘要
针对上游槽缝射流对涡轮端壁冷却性能影响的问题,同时考虑到涡轮端壁的气膜孔射流和叶栅通道间隙泄漏流同样对端壁及叶片吸力面存在冷却效果,采用数值求解三维Reynolds-Averaged Navier-Stokes(RANS)方程和SST k-ω湍流模型的方法,研究了带预旋上游槽缝射流0.4、0.6、0.8和1.0这4种旋流比和1.0、1.5和2.0这3种密度比对端壁冷却及叶片吸力面泛冷却(二次冷却)性能的影响特性。结果表明:密度比较小时,减小旋流比导致端壁冷却效果降低;密度比较大时,端壁冷却效果随旋流比减小先降低后升高,最低值出现在旋流比为0.8。随密度比的增加,冷却射流对端壁的冷却效果不断降低,冷却效率最低值随旋流比的增加向下游移动。随旋流比增大,槽缝射流对叶片吸力面泛冷却覆盖面积逐渐减小,位置向下游及靠近端壁的方向发展,泛冷却效率不断降低。随冷却射流密度比的增加,吸力面泛冷却面积显著减小,且向靠近端壁的方向移动,泛冷却效率降低。
The effects of four swirl ratios of 0.4,0.6,0.8 and 1.0 and three density ratios of1.0,1.5 and 2.0 in the upstream slot jet flow with preswirl on the turbine endwall cooling and suction surface phantom cooling performance are numerically investigated using the threedimensional Reynolds-averaged Navier-Stokes(RANS)equations and the SST turbulent model.The computational model of the turbine endwall taking into account the upstream slot jet flow,the film cooling on the endwall surface and the gap in the cascade passage is taken as the analysis objective.The results indicate that at a low density ratio,decreasing the swirl ratio of the slot jet flow has a negative effect on the endwall cooling effect.At a high density ratio,the cooling effect first decreases and then increases,with the minimum value appearing at the swirl ratio of 0.8.The density ratio has a negative effect on the cooling performance,and the position of the lowest effect moves downstream with the swirl ratio.By reducing the relative motion of the coolant androtor,the phantom cooling coverage of the slot jet flow becomes smaller and moves downstream,close to the endwall,which results in a lower phantom cooling effect.Increasing the density ratio of the coolant results in a smaller phantom cooling coverage which moves to the endwall,hence reducing the phantom cooling effect on the blade suction surface.
The effects of four swirl ratios of 0.4,0.6,0.8 and 1.0 and three density ratios of1.0,1.5 and 2.0 in the upstream slot jet flow with preswirl on the turbine endwall cooling and suction surface phantom cooling performance are numerically investigated using the threedimensional Reynolds-averaged Navier-Stokes(RANS)equations and the SST turbulent model.The computational model of the turbine endwall taking into account the upstream slot jet flow,the film cooling on the endwall surface and the gap in the cascade passage is taken as the analysis objective.The results indicate that at a low density ratio,decreasing the swirl ratio of the slot jet flow has a negative effect on the endwall cooling effect.At a high density ratio,the cooling effect first decreases and then increases,with the minimum value appearing at the swirl ratio of 0.8.The density ratio has a negative effect on the cooling performance,and the position of the lowest effect moves downstream with the swirl ratio.By reducing the relative motion of the coolant androtor,the phantom cooling coverage of the slot jet flow becomes smaller and moves downstream,close to the endwall,which results in a lower phantom cooling effect.Increasing the density ratio of the coolant results in a smaller phantom cooling coverage which moves to the endwall,hence reducing the phantom cooling effect on the blade suction surface.
引文
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[14]ZHANG Y,LI Y,YUAN X.Effects of inlet swirl on suction side phantom cooling[C]∥ASME Turbo Expo2016:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2016:V05CT19A027.
[15]CHEN A F,SHIAU C C,HAN J C.Turbine blade platform film cooling with simulated swirl purge flow and slashface leakage conditions[J].Journal of Turbomachinery,2017,139(3):031012.
[2]WRIGHT L M,GAO Z,YANG H,et al.Film cooling effectiveness distribution on a gas turbine blade platform with inclined slot leakage and discrete film hole flows[J].Journal of Heat Transfer,2008,130(7):071702.
[3]SURYANARAYANAN A,MHETRAS S P,SCHOBEIRI M T,et al.Film-cooling effectiveness on a rotating blade platform[J].Journal of Turbomachinery,2009,131(1):011014.
[4]DU K,LI J.Numerical study on the effects of slot injection configuration and endwall alignment mode on the film cooling performance of vane endwall[J].International Journal of Heat and Mass Transfer,2016,98:768-777.
[5]杜昆,李军,晏鑫.槽缝射流对静叶端壁冷却性能的影响[J].西安交通大学学报,2015,49(1):21-26.DU Kun,LI Jun,YAN Xin.Effect of the slot Jet impingement on the cooling performance of the vane endwall[J].Journal of Xi’an Jiaotong University,2015,49(1):21-26.
[6]MENSCH A,THOLE K A.Overall effectiveness of a blade endwall with jet impingement and film cooling[J].Journal of Engineering for Gas Turbines and Power,2014,136(3):031901.
[7]祝培源,宋立明,李军,等.间隙位置和几何对端壁冷却性能的影响[J].航空学报,2017,38(9):520942.ZHU Peiyuan,SONG Liming,LI Jun,et al.Effects of location and geometry of slot on film cooling performance of end-wall[J].Acta Aeronautica&Astronautica Sinica,2017,38(9):520942.
[8]李劲劲,何坤,晏鑫,等.透平叶片近前缘端壁处换热性能的研究[J].西安交通大学学报,2017,51(7):44-50.LI Jinjin,HE Kun,YAN Xin,et al.Investigation on the heat transfer performance of endwall near the blade leading-edge[J].Journal of Xi’an Jiaotong University,2017,51(7):44-50.
[9]杨星,刘钊,刘战胜,等.端壁通道间隙对端壁泄漏流冷却的影响[J].工程热物理学报,2017,38(1):44-48.YANG Xing,LIU Zhao,LIU Zhansheng,et al.Effects of mid-passage gap on endwall purge flow film cooling[J].Journal of Engineering Thermophysics,2017,38(1):44-48.
[10]杨星,刘钊,刘战胜,等.端壁错位对端壁泄漏流冷却的影响研究[J].工程热物理学报,2017,38(4):719-725.YANG Xing,LIU Zhao,LIU Zhansheng,et al.Effects of endwall misalignment on endwall purge flow film cooling[J].Journal of Engineering Thermophysics,2017,38(4):719-725.
[11]BARIGOZZI G,FRANCHINI G,PERDICHIZZI A,et al.Influence of purge flow injection angle on the aerothermal performance of a rotor blade cascade[J].Journal of Turbomachinery,2014,136(4):041012.
[12]MATTHEW S,GOLDSTEIN R J,SIMON T W,et al.Effect of swirled leakage flow on endwall film cooling[C]∥15th International Heat Transfer Conference.Kyoto,Japan:IHTC,2014:10-15.
[13]LI S J,LEE J,HAN J C,et al.Influence of mainstream turbulence on turbine blade platform cooling from simulated swirl purge flow[J].Applied Thermal Engineering,2016,101:678-685.
[14]ZHANG Y,LI Y,YUAN X.Effects of inlet swirl on suction side phantom cooling[C]∥ASME Turbo Expo2016:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2016:V05CT19A027.
[15]CHEN A F,SHIAU C C,HAN J C.Turbine blade platform film cooling with simulated swirl purge flow and slashface leakage conditions[J].Journal of Turbomachinery,2017,139(3):031012.