平行进口叶轮切割对混流泵作透平的影响

doi:10.16183/j.cnki.jsjtu.2019.081

摘要/Abstract

摘要：

为了探究叶轮切割对混流泵作透平的影响,设计一比转速为240的混流泵作透平,平行叶轮进口进行4次切割,切割同时保留透平叶轮的前后盖板,运用CFD与试验结合的方法得出混流泵作透平的外特性,分析叶轮切割对混流泵作透平的内部流动影响.结果表明:随着叶轮切割比例增加,混流泵作透平流量效率曲线向小流量工况偏移,在小流量区间,透平轴功率上升,扬程下降,在大流量区间透平轴功率下降,扬程上升.叶轮切割后叶轮与蜗壳间的循环流量增加,透平水力损失增加,因而透平最高效率下降.采用混流泵切割定律推测不同切割比例下透平高效点的外特性参数,发现推测所得外特性均高于试验值,但误差较小,混流泵叶轮切割定律可近似用于透平工况下叶轮切割的高效点预测.

关键词: 叶轮切割, 混流泵作透平, 数值模拟, 理论公式

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

中图分类号:

S277.9
TH311

杨孙圣, 邵珂, 戴韬. 平行进口叶轮切割对混流泵作透平的影响[J]. 上海交通大学学报, 2020, 54(8): 805-812.

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.

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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