Influence of Parallel Impeller Inlet Trimming on Mixed Flow Pump as Turbine

doi:10.16183/j.cnki.jsjtu.2019.081

Abstract

Abstract:

To study the influence of impeller trimming on mixed flow pump as turbine, a turbine whose specific speed is 240 is designed. The impeller inlet has been trimmed in parallel for four times and its shroud and hub are retained. By using the method of CFD and test, the turbine performance is obtained and the internal flow of the mixed flow pump as turbine is analysed. The result shows that with the increase in the trimming ratio, the best efficiency point moves to the small flow region. In the small flow region, the shaft power rises and the head drops. In the large flow region, the shaft power drops and the head rises. The circulation flow between the impeller and the volute increases so that the highest efficiency of the turbine decreases. The theoretical formulas are used to predict the performance of the mixed flow pump as the best efficiency point of the turbine, and the efficiency and head are higher than those in the test results, with smaller errors. It can be found that the formulas of the impeller trimming of mixed flow pump are almost suitable for the impeller trimming of mixed flow pump as turbine.

Key words: impeller trimming, mixed flow pump as turbine, numerical simulation, theoretical formula

CLC Number:

S277.9
TH311

YANG Sunsheng, SHAO Ke, DAI Tao. Influence of Parallel Impeller Inlet Trimming on Mixed Flow Pump as Turbine[J]. Journal of Shanghai Jiaotong University, 2020, 54(8): 805-812.

Figures/Tables 14

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References 19

[1]	陈凯, 杨孙圣, 王桃, 等. 叶轮外径对前弯型液力透平性能的影响[J]. 机械工程学报, 2016,52(22):198-204.
	CHEN Kai, YANG Sunsheng, WANG Tao, et al. Numerical research on impeller diameter influencing the performance of hydraulic turbine with forward-curved blades[J]. Journal of Mechanical Engineering, 2016,52(22):198-204.
[2]	SINGH P, NESTMANN F. An optimization routine on a prediction and selection model for the turbine operation of centrifugal pumps[J]. Experimental Thermal & Fluid Science, 2010,34(2):152-164.
[3]	SINGH P, NESTMANN F. Internal hydraulic analysis of impeller rounding in centrifugal pumps as turbines[J]. Experimental Thermal & Fluid Science, 2011,35(1):121-134.
[4]	SINGH P, NESTMANN F. Experimental investigation of the influence of blade height and blade number on the performance of low head axial flow turbines[J]. Renewable Energy, 2011,36(1):272-281. doi: 10.1016/j.renene.2010.06.033 URL
[5]	DERAKHSHAN S, NOURBAKHSH A. Experimental study of characteristic curves of centrifugal pumps working as turbines in different specific speeds[J]. Experimental Thermal & Fluid Science, 2008,32(3):800-807.
[6]	SEDLAR M, SOUKAL J, KOMAREK M. CFD analysis of middle stage of multistage pump operating in turbine regime[J]. Engineering Mechanics, 2009,16(9):413-421.
[7]	杨孙圣. 离心泵作透平的理论分析数值计算与实验研究[D]. 镇江: 江苏大学, 2012.
	YANG Sunsheng. Theoretical analysis, numerical simulation and experimental research on centrifugal pump as turbine[D]. Zhenjiang: Jiangsu University, 2012.
[8]	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. doi: 10.1016/j.renene.2012.06.002 URL
[9]	YANG S S, LIU H L, KONG F Y, et al. Experimental, numerical, and theoretical research on impeller diameter influencing centrifugal pump-as-turbine[J]. Journal of Energy Engineering, 2013,139(4):299-307. doi: 10.1061/(ASCE)EY.1943-7897.0000128 URL
[10]	YANG S S, KONG F Y, JIANG W M, et al. Effects of impeller trimming influencing pump as turbine[J]. Computers & Fluids, 2012,67:72-78.
[11]	YANG S S, LIU H L, KONG F Y, et al. Effects of the radial gap between impeller tips and volute tongue influencing the performance and pressure pulsations of pump as turbine[J]. Journal of Fluids Engineering, 2014,136(5):054501. doi: 10.1115/1.4026544 URL
[12]	杨军虎, 雷蕾, 张书玮, 等. 介质黏度对泵作透平时性能换算的影响[J]. 排灌机械工程学报, 2017,35(7):553-557.
	YANG Junhu, LEI Lei, ZHANG Shuwei, et al. Effect of medium viscosity on performance conversion of pump as turbine[J]. Journal of Drainage and Irrigation Machinery Engineering, 2017,35(7):553-557.
[13]	杨军虎, 王晓晖. 叶片形状对能量回收水力透平性能的影响[J]. 排灌机械工程学报, 2011,4(29):287-291.
	YANG Junhu, WANG Xiaohui. Effect of vane profile on hydraulic energy recovery turbines performance[J]. Journal of Drainage and Irrigation Machinery Engineering, 2011,4(29):287-291.
[14]	王桃, 孔繁余, 刘莹莹, 等. 叶片进口安放角对泵作透平外特性影响的数值模拟与验证[J]. 农业工程学报, 2017,33(15):98-104.
	WANG Tao, KONG Fanyu, LIU Yingying, et al. Numerical simulation and validation of effects of blade inlet angle on performance of pump-as-turbine[J]. Transactions of the Chinese Society of Agricultural Engineering, 2017,33(15):98-104.
[15]	王桃, 孔繁余, 陈凯, 等. 转速对离心泵作透平性能影响的试验与分析[J]. 农业工程学报, 2016,32(15):67-74.
	WANG Tao, KONG Fanyu, CHEN Kai, et al. Experiment and analysis of effects of rotational speed on performance of pump as turbine[J]. Transactions of the Chinese Society of Agricultural Engineering, 2016,32(15):67-74.
[16]	王桃, 孔繁余, 杨孙圣, 等. 泵作透平专用叶轮直径的确定及其对透平性能的影响[J]. 农业工程学报, 2016,32(15):60-66.
	WANG Tao, KONG Fanyu, YANG Sunsheng, et al. Determination of special impeller diameter for pump as turbine and its effects on turbine performance[J]. Transactions of the Chinese Society of Agricultural Engineering, 2016,32(15):60-66.
[17]	顾建明, 陆明琦. 离心泵叶轮切割对性能的影响[J]. 流体机械, 1994(5):12-15.
	GU Jianming, LU Mingqi. Influence of impeller trimming on the performance of centrifugal pump[J]. Fluid Machinery, 1994(5):12-15.
[18]	冀秀彦, 仲作文, 孙悦, 等. 高比转数混流泵叶轮的切割[J]. 中国农村水利水电, 2014(7):167-169.
	JI Xiuyan, ZHONG Zuowen, SUN Yue, et al. The trimming of high specific speed mixed flow pump[J]. China Rural Water and Hydropower, 2014(7):167-169.
[19]	关醒凡. 现代泵理论与设计[M]. 北京: 中国宇航出版社, 2011: 66-69.
	GUAN Xingfan. Modern pumps theory and design[M]. Beijing: China Aerospace Press, 2011: 66-69.

部件	参数	取值	部件	参数	取值
叶轮	叶轮出口直径D₁/mm	92	蜗壳	蜗壳基圆直径D₃/mm	140
	叶轮进口平均直径D₂/mm	115		蜗壳出口宽度b₃/mm	52
	叶轮轮毂直径D_h/mm	25		蜗壳进口直径D₄/mm	140
	叶片进口角β₂/(°)	55	尾水管	尾水管直径D₅/mm	100
	叶片出口角β₁/(°)	37.5		尾水管长度/mm	350
	叶轮进口宽度b₂/mm	34
	叶片数z	6

切割比例/%	Q/(m³·h^-1)	H/m	P/kW	η/%
0	109.22	5.75	1.21	71.02
5	99.61	5.04	0.84	68.91
10	95.24	4.45	0.77	67.10
15	90.00	3.96	0.64	65.70
20	84.76	3.63	0.53	63.36

叶轮切割比例/%	高效点流量/(m³·h^-1)		偏差/%	扬程/m		偏差/%
叶轮切割比例/%	理论计算	试验	偏差/%	理论计算	试验	偏差/%
0	-	109.22	-	-	5.75	-
5	103.76	99.61	4.17	5.19	5.04	2.98
10	98.30	95.24	3.21	4.66	4.45	4.72
15	92.84	90.00	3.16	4.15	3.96	4.80
20	87.38	84.76	3.09	3.68	3.63	1.38