EXPERIMENTAL AND THEORETICAL INVESTIGATION OF THE HEATING OF COMBUSTING DROPLETS IN A LINEAR STREAM

Combusting ethanol droplets in linear stream are investigated by two colors laser induced fluorescence. The technique enables us to follow the transient mean temperature evolution of the combusting droplets. A database, including a wide range of aerothermal injection parameters such as injection velocity, droplet diameter and inter-droplet distance (or non-dimensional distance parameter) is provided. A calculation based on the heat diffusion equation resolution, with a constant temperature fixed at the measured equilibrium temperature has been implemented. Both heat conduction and heat advection by the droplet internal motions have been taken into account, the inside droplet velocity field being modeled by the Hill vortex solution. The influence of the different injection parameters are discussed and the results are compared with the models usually available in the literature. The measurement relative to the droplets' transient heating enable to determine the Hill vortex intensity related to the maximum velocity at the droplet.