Mixing Nature of Supercritical Jet in Subcritical and Supercritical Conditions

In the present work, the injection of near-critical and supercritical fluid jet into subcritical and supercritical chamber conditions was performed. The main objective of the work was to investigate the transitional nature of the jet. The study was performed using planar-laser-induced-fluorescence technique to obtain the density and density-gradient field of the jet. The compound fluoroketone was used as the injectant fluid, and nitrogen and helium were used as chamber environments due to their difference in the critical-pressure values. The thermodynamic transition of the jet was analyzed using density and density-gradient-field maps. The fractal analysis of the supercritical jet was also performed to investigate the evolution of jet boundary in detail. The results indicated that the thermodynamic transition of the injected supercritical jet to liquid phase under subcritical chamber conditions never occurred in both nitrogen and helium chamber environments; the reason is attributed to the lower injectant density of the supercritical jet. The fractal nature of the jet was also investigated, and the jet boundary possesses fractal dimensions between 1.25 and 1.35, and is in good agreement with those reported elsewhere.