Abstract：To investigate the effect of runner cone length and shaft center hole water feeding on flow characteristics of draft tube, the SST turbulence model is used to simulate the three-dimensional unsteady flow in a Francis turbine. Under the rated condition, two cases, i.e. the original runner cone and a longer runner cone are simulated. Under the part-load condition, however, three cases are involved, namely, the original runner cone, the longer runner cone, and the longer cone with shaft center hole water feeding. The streamlines, pressure variations in various cross-sections in the tube, vortex rope and eddy viscosity of flow in these cases are analyzed. The results showed that under the rated working condition the lengthened runner cone can intensify the stability of the flow in the draft tube and improve the turbine efficiency slightly. Under the part-load condition, the lengthened runner cone can reduce the size of vortex rope in the tube but increase the eccentricity of the rope a bit. After a 2% rated flow water feeding is applied to the draft tube, the flow characteristics are improved significantly, the eddy viscosity of the flow in the straight diffusion section is lowered. Both the eccentricity and the rope size are decreased, but also the amplitude of low-frequency pressure pulsation caused by the eccentric vortex rope is reduced considerably.
赵道利*,高诚锋,孙维鹏,郭鹏程,马薇. 泄水锥加长与主轴中心孔补水对水轮机尾水管流态的影响[J]. 排灌机械工程学报, 2019, 37(5): 413-419.
ZHAO Daoli*, GAO Chengfeng, SUN Weipeng, GUO Pengcheng, MA Wei. Effect of runner cone length and shaft center hole water feeding on flow characteristics in draft tube. Journal of Drainage and Irrigation Machinery Engin, 2019, 37(5): 413-419.
[1]李仁年,蒋雷,李琪飞,等. 水泵水轮机增负荷过程尾水管内流场分析[J]. 排灌机械工程学报,2015,33(1):49-54. LI Rennian,JIANG Lei,LI Qifei,et al. Analysis of flow field in draft tube of pump-turbine during load increa-sing period[J]. Journal of drainage and irrigation machinery engineering, 2015,33(1):49-54.(in Chinese)[2]田晓庆,郑源,潘华辰,等. 涡流发生器对试验尾水管性能改善作用分析[J]. 排灌机械工程学报,2013,31(9):783-787. TIAN Xiaoqing,ZHENG Yuan,PAN Huachen,et al. Analysis on improvement of model draft tube by vortex-generators[J]. Journal of drainage and irrigation machinery engineering, 2013,31(9):783-787.(in Chinese)[3]齐继贺. 混流式水轮机尾水管涡带及压力脉动数值模拟[J].水资源与水工程学报,2017,28(3):168-172. QI Jihe. Numerical simulation of francis turbine draft tube vortex and pressure pulsation[J]. Journal of water resources & water engineering, 2017,28(3):168-172.(in Chinese)[4]FOROUTAN H, YAVUZKURT S. A partially-averaged Navier-Stokes model for the simulation of turbulent swirling flow with vortex breakdown[J]. International journal of heat and fluid flow, 2014,50:402-416.[5]冯建军,武桦,吴广宽,等. 偏工况下混流式水轮机压力脉动数值仿真及其改善措施研究[J]. 水利学报,2014,45(9):1099-1105. FENG Jianjun,WU Hua,WU Guangkuan,et al. Nume-rical simulation of pressure fluctuation in a Francis turbine at part load conditions with improved measures[J]. Journal of hydraulic engineering,2014,45(9):1099-1105.(in Chinese)[6]ZENG Yongzhong, LIU Xiaobing, WANG Huiyan. Prediction and experimental verification of vortex flow in draft tube of Francis turbine based on CFD[J]. Procedia engineering,2012,31(1):196-205.[7]ANUP K C,YOUNG Ho Lee,BHOLA Thapa. CFD study on prediction of vortex shedding in draft tube of Francis turbine and vortex control techniques[J]. Renewable energy,2016,86:1406-1421.[8]LITVINOV I, SHTORK S, GORELIKOV E, et al. Unsteady regimes and pressure pulsations in draft tube of a model hydro turbine in a range of off-design conditions[J]. Experimental thermal and fluid science,2018,91:410-422.[9]郭涛,张立翔. 混流式水轮机尾水管近壁湍流特性和流场结构研究[J]. 农业机械学报,2014,45(9):112-118. GUO Tao,ZHANG Lixiang. Numerical study of swirling flow fields in Francis turbine under small opening condition[J]. Transactions of the CSAM,2014,45(9):112-118.(in Chinese)[10]ARISPE T M, DE OLIVEIRA W, RAMIREZ R G. Francis turbine draft tube parameterization and analysis of performance characteristics using CFD techniques[J]. Renewable energy,2018,127:114-124.[11]SOSA J B, URQUIZA G, GARCIA J C,et al. Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube[J]. Advances in mechanical engineering, 2015,7(10):1-11.[12]刘育,余波,卿彪,等. 尾水管扩散段结构变化对低水头混流式水轮机性能的影响[J]. 水电能源科学,2014,32(10):147-150. LIU Yu,YU Bo,QING Biao,et al. Impact of change structure of draft tube diffuser on performance of low head Francis turbine[J]. Water resources and power,2014,32(10):147-150.(in Chinese) [13]刘树红,吴晓晶,吴玉林. 水轮机转轮泄水锥形状对机组内部流动影响分析[J]. 水力发电学报,2006,25(1):67-71,75. LIU Shuhong, WU Xiaojing, WU Yuling. Analysis of the influence of runner-hub shape on the internal flow in Francis turbine[J]. Journal of hydroelectric enginee-ring, 2006,25(1):67-71,75.(in Chinese)[14]MADDAHIAN R, CERVANTES M J, SOTOUDEH N. Numerical investigation of the flow structure in a Kaplan draft tube at part load[C]//Proceedings of the 28th IAHR Symposium on Hydraulic Machinery and Systems(IAHR2016), 2016.[15]DE HENAU V, PAYETTE F A, SABOURIN M, et al. Computational study of a low head draft tube and validation with experimental data[C]//Proceedings of the 25th IAHR Symposium on Hydraulic Machinery and Systems, 2010:012084.[16]李章超,常近时,辛喆. 射水减弱混流式水轮机尾水管内压力脉动的数值模拟[J]. 农业机械学报,2013,44(1):53-57. LI Zhangchao,CHANG Jinshi,XIN Zhe. Numerical simulation of elimination of pressure fluctuation in Francis turbine draft tube using water jet[J]. Transactions of the CSAM, 2013,44(1):53-57.(in Chinese)[17]QIAN Zhongdong, YANG Jiandong, HUAI Wenxin. Numerical simulation and analysis of pressure pulsation in Francis hydraulic turbine with air admission[J]. Journal of hydrodynamics, Ser B,2007,19(4):467-472.[18]陶文铨. 数值传热学[M]. 2版. 西安:西安交通大学出版社,2001.
