The Role of Orifice Design in Hydroentanglement

Abstract

This research was devoted to study the role of the nozzle geometry in the characteristics of hydroentangling waterjets. Three different conventional sharp-edge nozzle geometries, so-called cone-up, cone-down and cylindrical, under different pressures below 3500psi were examined. To exploit aforementioned nozzles, a single-waterjet test stand capable of working under manifold pressures up to 5000 psi was designed and built. Profiles of the waterjets produced by each of these nozzles were visualized by using a Nikon D1x digital camera and a regular light. The breakup lengths and the spray angles of the waterjets were extracted from the captured images by utilizing image analysis techniques and were compared with each other under different operating conditions.

It was revealed that the cone-up nozzle produces waterjets with considerably shorter intact lengths and slightly larger spray angles compared to the two other geometries considered. This distinct behavior was attributed to the cavitation-induced turbulence inside the cone-up nozzles. Discharge coefficients of the above nozzles were also measured versus injection pressures and showed a higher discharge coefficient for the cone-up nozzle compared to the others. The reason underlying these findings is attributed to the formation of the constricted waterjet in the cone-down and cylindrical nozzles.