Turbulence effects on evaporation rate-controlled spray combustor performance

We consider here the effects of gas-phase turbulence on the evaporation dynamics of a polydispersed dilute fuel spray in an adiabatic well-stirred reactor (WSR) supplied with hot compressed air. Turbulence increases the time-averaged rate of heat diffusion-controlled droplet evaporation but the augmentation factor is droplet size-dependent because of droplet inertia and evaporative drag reduction. Consequently, each droplet in a spray population will not be characterized by the same rate of area change even in the same time-averaged environment. When these physical phenomena are convoluted with the residence time distribution characterizing a WSR (simulating, say, the primary zone of an aircraft gas turbine combustor), we predict the resulting fraction evaporated, evaporation rate-controlled combustion “intensity”, and corresponding exit droplet size distributions (DSD).