|
|
|
| Experimental investigation into influence of clearance size on cavitating vortical flows in hydrofoil tip |
| LIU Leiming, LIU Ying, ZHAO Yu, WANG Guoyu |
| School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China |
|
|
|
|
Abstract Cavitating vortical flows in a hydrofoil tip with different tip clearance sizes are studied experimentally. A series of experiments are conducted in a closed-loop cavitation tunnel. The cavities are observed with a high speed camera and are analyzed by using image processing.The cavitating flow developing characters in the different size clearances(0.5 mm, 2.0 mm)are compared. Based on the results, three typical cavitation stages can be defined with decreasing cavitation number, namely incipient cavitation(I), attached cavitation(II), and shear layer cavitation(III). In stage I, the streamwise length of cavity in the big gap is larger than that in the narrow gap. In stage II, the attached cavity inside the large gap develops faster than that in the small gap in both the cavitation inception and the developing phases with decreasing cavitation number. In stage III, the critical cavitation number for the formation of triangular shear layer cavitation in the large gap is higher than that in the small gap; meanwhile, the cavity extends further downstream in the large gap than in the small gap as well.
|
|
Received: 18 November 2015
|
|
|
|
| [1]OWEIS G F, CECCIO S L. Instantaneous and time-averaged flow fields of multiple vortices in the tip region of a ducted propulsor[J]. Experiments in fluids, 2005, 38(5): 615-636.[2]TALLMAN J, LAKSHMINARAYANA B. Numerical simulation of tip leakage flows in axial flow turbines, with emphasis on flow physics: part I—effect of tip clearance height[J]. Journal of turbomachinery, 2001, 123(2): 314-323.[3]WU H, TAN D, MIORINI R L, et al. Three-dimensional flow structures and associated turbulence in the tip region of a waterjet pump rotor blade[J]. Experiments in fluids, 2011, 51(6): 1721-1737.[4]MIORINI R L, WU H, KATZ J. The internal structure of the tip leakage vortex within the rotor of an axial waterjet pump[J]. Journal of turbomachinery, 2012, 134(3): 031018.[5]黎耀军,沈金峰,严海军,等.叶顶间隙对轴流泵轮缘泄漏流动影响的大涡模拟[J].水利学报,2014,45(2):235-242. LI Yaojun, SHEN Jinfeng, YAN Haijun, et al. Investigation of the effects of tip-gap size on the tip-leakage flow in an axial-flow pump using LES[J]. Journal of hydraulic engineering, 2014,45(2):235-242.(in Chinese)[6]RAINS D. Tip clearance flows in axial flow compressors and pumps[D]. California,USA: California Institute of Technology, 1954.[7]HIGASHI S, YOSHIDA Y, TSUJIMOTO Y. Tip leakage vortex cavitation from the tip clearance of a single hydrofoil[C]//Proceedings of the CAV 2001: Fourth International Symposium on Cavitation, 2001.[8]HARWOOD C M, YOUNG Y L. A physics-based gap-flow model for potential flow solvers[J]. Ocean engineering, 2014, 88: 578-587.[9]LABORDE R, CHANTREL P, MORY M. Tip clearance and tip vortex cavitation in an axial flow pump[J]. Journal of fluids engineering, 1997, 119(3): 680-685.[10]李忠,杨敏官,姬凯,等.轴流泵叶顶间隙空化流可视化试验研究[J].工程热物理学报,2011,32(8):1316-1318. LI Zhong, YANG Minguan, JI Kai, et al. Visualization research on cavitation flow in tip clearance of axial-flow pump[J]. Journal of engineering thermophysics, 2011,32(8):1316-1318.(in Chinese)[11]施卫东,张华,陈斌,等.不同叶顶间隙下的轴流泵内部流场数值计算[J].排灌机械工程学报,2010,28(5):374-377. SHI Weidong, ZHANG Hua, CHEN Bin, et al. Nume-rical simulation of internal flow field in an axial flow pump with different blade tip clearance sizes[J]. Journal of drainage and irrigation machinery engineering, 2010, 28(5): 374-377.(in Chinese)[12]张德胜,吴苏青,施卫东,等.不同湍流模型在轴流泵叶顶泄漏涡模拟中的应用与验证[J].农业工程学报,2013,29(7):46-53. ZHANG Desheng, WU Suqing, SHI Weidong, et al. Application and experiment of different turbulence models for simulating tip leakage vortex in axial flow pump[J]. Transactions of the CSAE, 2013, 29(7): 46-53.(in Chinese)[13]张德胜,石磊,施卫东,等.轴流泵叶轮叶顶区空化流的数值模拟与试验研究[J].水利学报,2014,45(3):335-342. ZHANG Desheng, SHI Lei, SHI Weidong, et al. Numerical simulation and experimental study on impeller tip region cavitation in axial flow pump[J]. Journal of hydraulic engineering, 2014, 45(3): 335-342.(in Chinese)[14]张德胜,陈健,张光建,等.轴流泵叶顶泄漏涡空化的数值模拟与可视化试验研究[J].工程力学,2014,31(9): 225-231. ZHANG Desheng, CHEN Jian, ZHANG Guangjian, et al. Numerical simulation and visualization study on tip leakage vortex cavitation in an axial-flow pump[J]. Engineering mechanics, 2014,31(9): 225-231.(in Chinese)[15]DUCOIN A, ANDRE A J, SIGRIST J F. An experimental analysis of fluid structure interaction on a flexible hydrofoil in various flow regimes including cavitating flow[J]. European journal of mechanics-B/fluids,, 2012, 36: 63-74.[16]韩宝玉,熊鹰,刘志华.梢涡空化CFD数值方法[J].哈尔滨工程大学学报,2011,32(6):702-707. HAN Baoyu, XIONG Ying, LIU Zhihua. Numerical study of tip vortex cavitation using CFD method[J]. Journal of Harbin Engineering University, 2011, 32(6): 702-707.(in Chinese)[17]LEE T, PEREIRA J. Nature of wakelike and jetlike axial tip vortex flows[J]. Journal of aircraft, 2010, 47:1946-1954. |
|
|
|
