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| Experimental study on calculation method of local head loss in thin-wall drip irrigation pipes with non-coaxial emitters |
| WANG Jian*, WEI Tao, YANG Ting, YUAN Shouqi |
| National Research of Pumps, Jiansu university, Zhenjiang, Jiangsu 212013, China |
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Abstract The local head loss of non-coaxial emitters in five thin-wall drip irrigation pipes with standard diameter of 16 mm was studied by conducting hydrodynamic experiment. The variation of the ratio of local head loss to friction head loss along the drip irrigation pipe, hjt/hf, and the local head loss coefficient α, were analyzed. The results show that under the same working pressure, the equivalent diameter of drip irrigation pipe decreases with the increase of wall thickness, resulting in the increase of friction head loss and local head loss along the drip irrigation pipe. The local head loss is related to wall thickness, emitter cross section area and Reynolds number. With the increase of Reynolds number, the ratio of local head loss to friction head loss along the drip irrigation pipe(hjt/hf,)decreases. The minimum value reaches 0.67, but it still exceeds the design standard of Chinas technical specification for micro-irrigation engineering(0.1-0.2). Based on the multiple regression analysis of the test data, the relationship between the local head loss coefficient and the contraction ratio of cross section and Rey-nolds number is proposed, and the correlation coefficient is 0.96.
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Received: 05 August 2019
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