ABSTRACT
The evaporation of drops in a spray involves simultaneous heat and mass transfer processes in which the heat for evaporation is transferred to the drop surface by conduction and convection from the surrounding hot gas, and vapor is transferred by convection and diffusion back into the gas stream. In most practical combustors the fuel leaves the nozzle in the form of ligaments or shreds that rapidly disintegrate into drops of varying size. The term steady state is perhaps a misnomer when applied to drop evaporation, because a fuel drop may not attain steady-state evaporation during its lifetime. The development of drop evaporation theory was largely motivated by the needs of the aero gas turbine and the liquid propellant rocket engine. For most practical fuels, the heat-up period constitutes an appreciable proportion of the total drop lifetime. Drop evaporation times are also important in the design of premix-prevaporize combustors for gas turbines, since they govern the length of the prevaporization passage.
