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Effect of outlet back pressure on performance of twin-screw pump as turbine |
JIANG Xiaoping, LIU Sihan, WANG Yang, WU Jiahui, LI Wei, ZHU Jiawei |
National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract There is little study on screw pump as turbine even though the pump potentially can be applied in process industry, especially in liquid-gas two-phase flow conditions. On account of this serious shortage of research in this field, fluid dynamics in a twin-screw pump with the commonly used A-type tooth profile and specific geometrical parameters was simulated by employing moving mesh technique in a CFD code-Pumplinx when the pump working as turbine. Firstly, the mesh was generated, and then a mesh size independency analysis was conducted to get the optimal meshing scheme; finally, the characteristics of the pump as turbine were obtained and compared between various outlet back sta-tic pressures. The results showed that the fluid static pressure in the turbine always kept being a step shape from the inlet to the outlet of the screws due to the influence of meshing line, but also the fluid static pressures in the sealing chambers were in the same level as those in the screws. The interlobe clearance and radial gap between the casing and the screw tip were two chief factors affecting the efficiency of the turbine, especially with the increase of outlet back pressure, the leakage flow rate and velocity decreased, resulting in an increased efficiency. Meanwhile, the torque and axial thrust on the screws were affected significantly and directly by the back pressure, particularly, they decreased linea-rly with increasing back pressure. However, compared with the follower screw, the main screw could produce a more torque and withstand a larger axial thrust.
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Received: 28 September 2016
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[1]LIU W, LUND H, MATHIESEN B V, et al. Potential of renewable energy systems in China[J]. Applied energy, 2011, 88(2):518-525.[2]LI F. Hydropower in China[J]. Energy policy, 2002, 30(14):1241-1249.[3]VARU N, PRAKASH R, BHAT I K. Energy, economi-cs and environmental impacts of renewable energy systems[J]. Renewable & sustainable energy reviews, 2009, 13(9): 2716-2721.[4]ORCHARD B, KLOS S. Pumps as turbines for water industry[J]. World pumps, 2009(8):22-23.[5]LAN Y, LIU B, WU Z. Present and future power genera-tion in China[J]. Nuclear engineering & design, 2007, 237(12): 1468-1473.[6]蒋小平,刘思晗,叶剑斌,等. 高压余能回收液力透平试验台开发[J].流体机械,2017,45(6):44-48. JIANG Xiaoping,LIU Sihan,YE Jianbin,et al. Development on test system of hydraulic turbine to high pressure surplus energy[J]. Fluid machinery, 2017,45(6):44-48.(in Chinese)[7]BARBARELLI S, AMELIO M, FLORIO G. Predictive model estimating the performances of centrifugal pumps used as turbines[J]. Energy, 2016, 107:103-121.[8]JAIN S V, SWARNKAR A, MOTWANI K H, et al. Effects of impeller diameter and rotational speed on performance of pump running in turbine mode[J]. Energy conversion & management, 2015, 89:808-824.[9]YANG S S, DERAKHSHAN S, KONG F Y. Theoretical, numerical and experimental prediction of pump as turbine performance[J]. Renewable energy, 2012, 48:507-513.[10]YANG S S, KONG F Y, CHEN H, et al. Effects of blade wrap angle influencing a pump as turbine[J]. Journal of fluids engineering, 2012, 134(6):061102.[11]杨孙圣,孔繁余,陈浩,等. 叶片进口安放角对液力透平性能的影响[J]. 中南大学学报(自然科学版),2013,44(1):108-113. YANG Sunsheng, KONG Fanyu, CHEN H, et al. Effects of blade inlet angle on performance of pump as turbine[J]. Journal of Central South University(natural science edition), 2013, 44(1): 108-113.(in Chinese)[12]杨孙圣,孔繁余,成军,等. 液力透平蜗壳内非定常压力脉动的研究[J]. 工程力学,2013,30(2):388-393. YANG Sunsheng, KONG Fanyu, CHENG J, et al. Research on unsteady pressure field within a hydraulic turbine volute [J].Engineering mechanics,2013, 30(2):388-393.(in Chinese)[13]杨军虎,李泰龙. 蜗壳结构对液力透平径向力的影响[J].排灌机械工程学报,2015,33(8): 651-655,680. YANG Junhu,LI Tailong. Influence of volute configurations on radial force of hydraulic turbine[J].Journal of drainage and irrigation machinery engineering,2015,33(8): 651-655,680.(in Chinese)[14]杨军虎,张雪宁,王晓晖,等. 能量回收液力透平研究综述[J]. 流体机械,2011,39(6): 29-33. YANG Junhu, ZHANG Xuening, WANG Xiaohu, et al. Overview of research on energy recovery hydraulic turbine[J]. Fluid machinery, 2011, 39(6):29-33.(in Chinese)[15]ZHU Baoshan, WANG Xuhe, TAN Lei, et al. Optimization design of a reversible pump—turbine runner with high efficiency and stability[J]. Renewable energy, 2015, 81:366-376.[16]PUGLIESE F, PAOLA F D, FONTANA N, et al. Experimental characterization of two pumps as turbines for hydropower generation[J]. Renewable energy, 2016, 99: 180-187. |
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