INFLUENCE OF GEOMETRICAL PARAMETERS OF LABYRINTH FLOW PATH OF DRIP EMITTERS ON HYDRAULIC AND ANTI-CLOGGING PERFORMANCE

摘要

Geometric patterns are used to create a labyrinth-style flow path within drip emitters in the manufacturing process. The labyrinth pathway helps in dissipating energy as water travels to the emitter opening and at the same time maintains a turbulent flow condition that facilitates movement of paniculate material out of the system to avoid clogging. In this study, emitters were designed and constructed using variable geometric parameters. These drip emitters were tested for hydraulic performance and anti-clogging ability using the ISO protocol for emitter testing. Parameters tested in the design and manufacture were dentation angles (104°, 108°, 112°, 117°), spacing between dentations (1.5, 1.8, 2.1, 2.5 mm), dentation heights (1.0, 1.3, 1.6, 1.9 mm), and depth of flow passages (0.6, 0.9, 1.2, 1.5 mm). An orthogonal array was used to determine statistically useful combinations of all parameters to avoid unmanageable numbers of emitters, and subsequent tests involved eight phases with eight levels of mixtures of macro grit concentration. Sixteen combinations were found useful, and accordingly 16 types of emitters were built and used to manufacture drip tubes. Test results of these 16 drip emitters show that spacing between dentation had a significant influence on the exponential (x) value of flow state and the anti-clogging ability of the emitter. The anti-clogging ability of an emitter was not linearly correlated with the flow rate but was significantly affected by the shape of the labyrinth flow path determined by dentation spacing, angle, and height. Results also indicate that the chance of an emitter being plugged by sand particles is small if filters are selected according to the rule of using screen openings of 1/10 the width of the flow passage.