Effect of Nozzle Geometry on the Flow Dynamics of Hydroentangling Jet

Hydroentangling technique uses extremely fine nozzles to direct high-energy water jets against a loose fiber web. This study investigates the effect of nozzle geometry on the flow dynamics of hydroentangling jet by simulating water-jet formation from cone-up, streamline, and cone-down geometries. The simulation results reveal that water contacts with the nozzle wall all the way when it goes through the cone-up and streamline nozzles. In contrast, the cone-down geometry can form a constricted water-jet because of a sharp turning angle at the nozzle entrance. Consequently, the cone-down nozzle has higher velocity coefficient and the water-jet discharged from the nozzle has a longer intact length than the two others because of the absence of cavitation and wall friction. Part of the results is in excellent agreement with earlier experimental studies.