Study On The Hydraulic Characteristic And Optimal Design Of The Gravitational Flexible Hose Micro-irrigation Field Pipe Network

The technology of gravitational flexible hose micro-irrigation is a kind of simple and practical saving irrigation technology in the inadequate economic technological condition. This technology is applied in an irrigation area that is a nature field, and the gravity irrigation is realized by the water head formed by the slope of the field surface and the water head difference between the irrigation channel and the field surface. Pipe network of the gravitational flexible hose micro-irrigation is constructed by the two level hoses consisted of branch pipe and capillary or by the three level hoses consisted of main pipe,branch pipe and capillary. This technology with its advantages of small investment,low fluid matter demandment,energy conservation,easy operation and strong practicality is rapidly promoted and applied in Xinjiang region.Capillary is the core and the key to the gravitational flexible hose micro-irrigation technology. Based on the indoor experiment, the impacts of the various factors on the capillary flowing out uniformity are analyzed in the paper. Considering the system of working in turns, the main pipe and branch pipe are divided into two parts which are constant discharge along the distance and variable discharge along the distance. According to the hydraulic models and calculation formulas of the capillary variable discharge along the distance, the calculation formulas of the head loss along the distance,the pressure head distribution along the distance,the orifice discharge, and the laying length design methods of the main pipe and branch pipe are given out.Drawing on the pressurized irrigation planning design, the methods and steps of the gravitational flexible hose micro-irrigation network system design are given. Optimum mathematical models of the minimum weight objective function are separately set up for the main pipe,branch pipe and capillary, then optimum mathematical model of the minimum investment objective function is also established for the whole pipe network system. The capillary double way water entering design is provided in the paper, and the hydraulic characteristic is theoretically analyzed comparing with the capillary single way water entering and double way water entering. The impact on the capillary flowing out uniformity and the capillary laying length in the capillary double way water entering condition is concretely analyzed, and the hydraulic calculation method of the network in the capillary double way water entering condition is given. At last terrain applicable condition,small irrigation controlling area and the system controlling area for the common using layout structure pipe networks are comparatively analyzed, and their investments are compared through the examples. The investment differences of the entire pipe network system in the capillary single way water entering and double way water entering condition are also given out through the examples.This topic originates from the National Natural Science Foundation of China subsidization project.