Wear Behavior and Vortex Characteristics of Y-Type Screen Filters with Various Inclination Angles and Inlet Flow Velocities: Numerical and Experimental Study

Y-type screen filters are widely used in microirrigation systems. Their good hydraulic performance and working life are the premise to ensure the normal and stable operation of microirrigation systems. In addition to the particle impurities in the fluid affecting the performance of the filter, the energy loss of the vortex in the flow field is also an important factor. This study explored the flow field, vortex characteristics, and wear of a Y-type screen filter under various operating conditions and design parameters. In particular, the fluid mechanics discrete-element method was used to numerically simulate the flow characteristics and wear characteristics of five Y-type screen filter inlet velocities (0.5, 0.75, 1, 1.25, and 1.5 m/s) and five Y-junction angles (35°, 40°, 45°, 50°, and 55°) using computational fluid dynamics. The numerical simulation results were experimentally verified. With increased inlet velocity, the strong vortex extended from the filter screen to the outlet pipe. At a maximum velocity of 1.5 m/s, the vorticity degree rose by 51.49% compared with that at a minimum velocity of 0.5 m/s, and the helicity distribution slightly changed. With the increased angle of the Y-section, the vorticity in the filter also increased. The increase of the Y-junction angle from a minimum value of 35° to a maximum of 55° angle resulted in a vorticity degree rise by only 10.64%. The positive vortex area of the outlet pipe decreased with the filter angle. The Q-criterion vortex identification method revealed that high-intensity vortices were mainly distributed on the mesh of the filter screen. Through numerical simulation prediction and experimental verification by wear tests, it was found that the parts with the largest wear depth were the outlet side filter screen and shell cover area, and the wear depth increased with the flow rate. At 2 s, the wear depth at the maximum flow rate significantly exceeded that at the minimum one. After a certain period of time, the wear depth of the Y-type screen filter increased with the Y-junction angle. In practical applications, the filter with an angle of 35° was selected for operating at low flow rates below 1 m/s. Hence, its internal flow field was more moderate, and its hydraulic performance improved, reducing the filter screen wear and prolonging its service life.