Hydraulic Property and Flow Characteristics of Three Labyrinth Flow Paths of Drip Irrigation Emitters under Micro-Pressure

A bstract. Lowering the working pressure of emitters is a potential approach to reducing the cost and operational expenditure of drip irrigation systems. Because of the lack of micro-pressure emitter molds, assembly lines, and micro-pressure emitter design theory, it is rare to find special emitters for micro-pressure drip irrigation. Taking three kinds of currently familiar labyrinth flow path emitters as the research object, a computational fluid dynamics (CFD) model for simulating the internal fluid flow within a micro-pressure labyrinth flow path was used to explore the integration of digital particle-tracking velocimetry and plane laser inducement fluorescence velocimetry for measuring the internal flow field of the labyrinth flow paths of emitters. The relative difference between the CFD-simulated discharge and the practically measured free discharge was less than 10.0%. Compared with the DPIV-measured results, the error was relatively small in terms of velocity distribution and magnitude of high and low velocity regions. The proposed physical model for internal fluid flow and its solution method could relatively accurately simulate the internal fluid flow characteristics and predict hydraulic property parameters under micro-pressure (10 to 50 kPa). The flow within three kinds of flow paths under micro-pressure was turbulent. It is possible to select a suitable flow path pattern to realize a full-turbulence design for special emitters under micro-pressure.