Correlation analysis of superheated liquid jet breakup to bubble formation in a transparent slit nozzle

This investigation is to evaluate and quantify the influence of bubble formation inside the nozzle on breakup characteristics of a superheated liquid jet outside the nozzle. The effect of fuel properties was examined using methanol, ethanol and butanol. A unique optically-transparent slit nozzle with a high-speed micro-imaging system were utilized for quantifying the bubble formation inside and the liquid jet breakup outside the nozzle. Correlation between bubble number density and breakup of superheated liquid jet was obtained for all the fuel. The bubble is demonstrated as the main driving forces enhancing the breakup of superheated liquid jet. By introducing a parameter K, it is easier to correlate the superheated liquid jet breakup to the bubble number density as Δf = K ⋅ n. K is related with the superheat degree, Reynolds number, Weber number, and the ratio of liquid to ambient gas viscosities, which has different form at the transition stage (0.2 < Pa/Ps ⩽ 0.3) and the flare flashing stage (Pa/Ps ⩽ 0.2), implying different breakup regimes.