Abstract:For hydraulic design of drip irrigation lateral to be improved, the minor head loss caused from online emitters in drip irrigation laterals was explored experimentally. Based on the experimental results, the minor head loss coefficient ξ and the ratio of the minor head loss over the frictional head loss, hj/hf, were correlated to Reynolds number and emitter spacing for different types of emitter. It was shown that hj/hf is considerably dependent on type of emitter and emitter spacing. At the same emitter spacing, hj/hf caused from online labyrinth channel emitters is greater than that from pressure compensating emitters; for the same type of emitters, however, hj/hf is inversely proportional to emitter spacing. Importantly, all the hj/hf values are larger than those specified in the Technical Standard of MicroIrrigation Project (SL-103-95). According to the standard, the minor head loss is about (0.1-0.2)% of the total frictional head loss; obviously the total head loss will be underestimated by this. Further, the minor head loss coefficient ξ are related to the type of emitter, Reynolds number and emitter spacing. For labyrinth channel emitters the coefficient is higher than 0.6; however, for compensating pressure emitters, it is ranged in 0.3-0.5. The coefficient increases with decreasing emitter spacing, and declines with increasing Reynolds number. An empirical formula for the coefficient was proposed by regression.
仇振杰, 朱德兰, 张林. 滴头插入对滴灌毛管水头损失影响试验研究[J]. 排灌机械工程学报, 2013, 31(3): 265-269.
CHOU Zhen-Jie, ZHU De-Lan, ZHANG Lin. Experimental study on effect of online emitter on head loss in drip irrigation laterals. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(3): 265-269.
[1]Yildirim G. An assessment of hydraulic design of trickle laterals considering effect of minor losses[J]. Irrigation and Drainage, 2007,56(4):399-421.[2]Provenzano G,Pumo D. Experimental analysis of local pressure losses for microirrigation laterals[J]. Journal of Irrigation and Drainage Engineering,2004,130(4):318-324.[3]吴政文,张学军.微喷带沿程水头损失的试验研究[J].节水灌溉,2011(8):40-42.Wu Zhengwen,Zhang Xuejun. Experimental study on frictional head loss of microsprinkling hose[J]. Water Saving Irrigation, 2011(8): 40-42. (in Chinese)[4]Dogan E, Kirnak H. Water temperature and system pressure effect on drip lateral properties[J]. Irrigation Science, 2010,28(5):407-419.[5]AlAmoud A I. Significance of energy losses due to emitter connections in trickle irrigation lines[J]. Journal of Agricultural Engineering Research, 1995,60(1):1-5.[6]Yildirim G. Total energy loss assessment for trickle lateral lines equipped with integrated inline and online emitters[J]. Irrigation Science, 2010,28(4):341-352.[7]Thompson E J, Merkley G P, Keller A A, et al. Experimental determination of the hydraulic properties of lowpressure, layflat drip irrigation systems[J]. Journal of Irrigation and Drainage Engineering, 2011,137(1):37-48.[8]吴持恭.水力学(上册)[M]. 4版. 北京:高等教育出版社,2008:132.[9]Vekariya P B, Subbaiah R, Mashru H H. Hydraulics of microtube emitters: A dimensional analysis approach[J]. Irrigation Science, 2011,29(4):341-350.[10]吴玉明. 局部阻力产生的原因和采取的措施[J]. 长春理工大学学报:高教版,2008,3(1):175-177.Wu Yuming. Brief talking about the cause of partial resistance and the taken measures[J]. Journal of Changchun University of Science and Technology: Higher Education Edition,2008,3(1):175-177. (in Chinese)[11]贺益英,赵懿,孙淑卿,等.输水管线中弯管局部阻力的相邻影响[J].水利学报,2004(2):17-20.He Yiying,Zhao Yi,Sun Shuqing,et al. Interaction of local loss between bends in pipe line[J]. Journal of Hydraulic Engineering,2004(2):17-20.(in Chinese)