Effects of Flow Path Geometrical Parameters on the Hydraulic Performance of Variable Flow Emitters at the Conventional Water Supply Stage

We created a subsurface drip irrigation (SDI)-specific variable flow emitter (VFE) that switches working stages automatically based on the inlet pressure (H) to achieve step change in rate. At stage I (H = 0.1 MPa), namely conventional water supply stage, VFE provided normal rate (qI) of 1–2 L/h for crop irrigation. II > MPa; exceeding design pressure), delivered larger (qII). The qII facilitated movement upward from underground surface seedbed during planting, thus ameliorating germination issues under SDI. focused impacts four structural parameters channel: tooth height (E), spacing (B), angle (A), and channel depth (D) qI VFE-flow index (x) at I. Computational fluid dynamic (CFD) simulations were conducted along with physical laboratory test develop using computerized numerical control (CNC) technology (accuracy 0.05 mm). Nine VFEs designed an L9(34) orthogonal test. combination tetrahedral meshing six-layer boundary layer realizable k–ε turbulence model was found suitable CFD simulations. standard root-mean-square error (nRMSE) measured simulated qIs minimum 7.4%. influenced as D B E A, factors xs A. Based simulation data, multiple linear regression models constructed when H MPa. Aiming x, optimal corresponding different determined by ergodic optimization algorithm. When 1.5 L/h, combinations 1.2 mm, 1.8 A 42°, 1 mm. CNC technology. relative errors predicted −0.19–6.31%, their nRMSE 6.76%. Thus, optimizing algorithm is highly precise theoretical base development.