Breakup of a power-law liquid sheet formed by an impinging jet injector

Abstract

Gel propellant is promising for future aerospace application, but because it behaves as the non-Newtonian power-law liquid, it is difficult to atomize. Impinging jet injectors are often used for atomization of gelled propellant. To understand the atomization mechanism of gelled propellant, a linear instability analysis method was used to investigate the instability and breakup characteristics of the sheet formed by a gelled propellant impinging-jet injector. The maximum disturbance wave growth rate and dominant wave number were determined by solving the dispersion equation of a power-law liquid sheet. It was found that the maximum disturbances growth rate and the dominant wave number both increase as Weber number of the liquid sheet increases. Consistency coefficient and flow index were tested for their influence on the stability of the power-law liquid sheet. A modified model, to predict the breakup length and critical wavelength of the power-law liquid sheet, was adopted. To validate the power-law liquid sheet breakup model, experiments were performed with injectors of different configurations and a high speed camera was used to show detailed information of the liquid sheet breakup process. The rheology of the power-law fluid used in the present study was also investigated. Comparison between the theoretical and experimental results shows that the linear instability analysis method can be applied to predict breakup length and wavelength of the power-law liquid sheet.