Metastable flow of water through submerged orifice

The flow of water through submerged orifice under several conditions was investigated. The flow was characterized by measurement of the flow rate - pressure drop relationship. The primary interest of the work was to obtain superheated liquid at the inlet and at the exit of the orifice. The metastable state then existing was studied with respect to its stability. The disturbance of the metastable state was verified to occur due to nucleation or the introduction of a bubble into the liquid. This nucleation showed strong dependence on the turbulence created by the discontinuity of velocity between the jet and the surrounding liquid. The existence of nucleation in the superheated liquid gives origin to different patterns of flashing. An insight in these patterns was obtained using the recourse of the high-speed photography motion picture technique.