2018 年 3 巻 p. 92-97
A two-phase converging-diverging nozzle is a device converting the thermal energy of a liquid-gas flow at the inlet to the kinetic energy of supersonic flow at the outlet. The pressurized dissolution method is one of the micro-bubble generation methods, by reducing the pressure of the water after the water had been saturated with gas under a high pressure. In the previous study, the pressurized dissolution method using a converging-diverging nozzle was used to generate a supersonic flow but it didn’t succeed. Therefore, the pressurized dissolution method was modified by connecting two converging-diverging nozzles in the present study. The aim of connecting two nozzles is to generate a two-phase flow before the downstream nozzle because one nozzle makes only single phase flow at the throat. As increasing the CO2 dissolved gas rate, the many bubbles were generated and the void fraction also increased but the liquid velocity decreased at the throat. Therefore, the study shows the proper condition to obtain a supersonic flow.
