Hydrodynamics Characteristics of High Speed Multi-Phase Flow in AWJ Nozzles. 1st Report, Analytical Model and Comparison with Experimental Data.

This paper describes the hydrodynamic characteristics of the abrasive water jet (AWJ) flowing within smallbored nozzles. For analyzing high-speed water jet containing fine solid particles, we introduce the slip velocity model to the one-dimensional momentum equation and estimate the axial distribution of pressure and phase-velocities within the nozzle. The analytical result shows that (1) the pressure within nozzle is always in the vacuum side in case of high-speed water jet and (2) the pressure along the nozzle axis is greatly affected with the change in slip ratio. Experimental data using high-speed two speed two-phase flow of air-water mixture coincide with these predicted tendency. The data also show that there is steep pressure rise at the nozzle exit. From the data analysis, it is concluded that gas phase velocity exceeds its sonic velocity in some region within the nozzle and the phenomena like as normal shock wave may occur in the AWJ nozzle.