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| DOI：10.13522/j.cnki.ggps.20180377 |
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| Hydraulic Characteristics at the Confluence of Two Submersible Pumps in Center-pivot Irrigation |
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ZHANG Yunlong, YAN Haijun, WANG Jiandong
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1. College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China; 2. Department of Irrigation and Drainage, China Institute of Water Resources and Hydropower Research, Beijing 100048, China
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| Abstract: |
| 【Objective】 Double submersible pumps are often used in parallel in center-pivot irrigation to meet the requirement for flow rate, with a confluence device installed to regulate the inlet flow rate and stabilize the working pressure. The purpose of this paper is to analyze the hydraulic characteristics at the confluence. 【Method】The study was based on numerical simulation, in which we examined the impact of Reynolds number and the confluence ratio (ratio of the maximum flow rate to the minimum flow rate at the inlet) on the hydraulic characteristics at the confluence. 【Result】It was found that the relative error of the simulated hydraulic loss at the confluence was in the range of 0.5% to 3.3%, compared to the experimental measurement. The hydraulic loss was quadratically related to the Reynolds number and the confluence ratio, with minimum hydraulic loss achieved when the confluence ratio was 0.8. In addition, the local resistance coefficient at the two inlets was independent of the Reynolds number, but changed with the confluence ratio. When the confluence ratio varied between 0.2 and 1.0, the local resistance coefficient varied between 1.16 and 1.31 at the large flow inlet, and between 1.31 and 4.22 at the small flow inlet. 【Conclusion】 The structure and hydraulic performance of the confluence can be used in engineering design and operational management of the center-pivot irrigation system. |
| Key words: center-pivot irrigation system; confluence device; numerical simulation; local resistance coefficient; confluence ratio |
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