Heat transfer within combusting droplets

The improvement of the basic understanding of heat transfer in sprays is a key point in many engineering applications. In this paper, the temperature field within combusting ethanol droplets in linear stream is investigated by the two-color laser induced fluorescence technique. Additionally, a heat transfer model within the droplet is developed, taking into account both heat conduction and heat advection by the droplet internal fluid circulation, according to the Hill vortex pattern. Heat and mass exchanges between the liquid and the gas phases are described within the framework of the quasi-steady approach and the film theory. Comparisons between measurements and computational results allow determining the intensity of the Hill vortex related to the maximum velocity at the droplet surface. An expression of the friction coefficient for combusting and interacting droplets is derived from the case of an isolated droplet and a good agreement with the experimental data is observed.