Sensitivities in the modeling of electrostatically charged droplet evaporation and combustion

Electrostatic charging has the potential to enhance droplet evaporation in liquid-fueled combustion applications. Based on well-established experimental evidence, it is known that as an electrostatically charged droplet evaporates and approaches the Rayleigh limit, it fragments into a residual droplet and a number of other sibling droplets. This process can reduce the total vaporization time. In the context of combustion, the produced sibling droplets will burn, reducing the vaporization time of the charged residual due to heat release; however, this process has not been studied in the literature. In this paper, a traditional droplet-evaporation model is extended to account for the influence of reacting sibling droplets on the vaporization and electrostatic atomization of an electrified residual droplet. The single-droplet modeling approach with and without charge is initially validated against existent experimental data and is in excellent agreement with published results. The sensitivity of the model that accounts for burning sibling droplets is subsequently assessed with respect to key parameters of experimental relevance. These include the number of siblings n, initial droplet charge with respect to the Rayleigh limit Q0/Qray, and residual droplet charge with respect to the primary droplet charge Q1/Q0, as well as the Reynolds number. This simple yet new approach highlighted here sheds light on the relevance of different electrostatic and physical parameters on the modeling of electrostatically charged droplet evaporation in reacting and nonreacting settings.