Instability breakup model of power-law fuel annular jets in slight multiple airflows

Abstract

In this paper, a temporal instability model has been derived to explore the influence of slight multiple airflow movements for the power-law fuel annular jet. Adopting the method of linear approximation and considering two different disturbance modes, the power-law fuel jet dispersion equation has been obtained based on the initial and boundary conditions. The influence of dimensionless characteristic parameters for the annular jet is investigated. By solving the dispersion equation, it can be found that the para-sinuous mode is more likely to play a leading role. For low-speed cases, the outer crossflow gas promotes the instability of fuel annular jets more effectively, while the inner coaxial airflow has an obvious promotion impact on high-speed jets. Reducing the thickness of the fuel annular film will weaken the stable inertia of the fuel, make the fuel annular jet easier to break up, and enhance the primary breakup scale. Furthermore, increasing the outer or inner gas density can accelerate the annular spray breakup process, and also amplify the gain effect of airflows. Besides, pseudoplastic fluid annular jets are more unstable and more suitable as fuel for future use. These discussions aim for a better understanding of the power-law fuel annular jet breakup process with multiple airflows and provide theoretical guidance for practical applications.