Computations of Turbulent Evaporating Sprays

A computational study of turbulent evaporating sprays is reported. The major focus is to study the structure of turbulent evaporating sprays and to examine the sensitivity of their vaporization behavior to transient liquid-phase processes. Three models considered to represent these processes are the thin-skin, infinite-diffusion, and diffusionlimit models. Favre-averaged equations with a k-s-g turbulence model are employed for the gas phase. The Lagrangian approach with a stochastic separated-flow method is used for the liquid phase where the effects of gas turbulence on droplet trajectories and interphase transport rates are considered using random-walk computations. Variable-property effects are also considered in a comprehensive manner. Results indicate that, depending upon the boiling temperature and heat of vaporization of the fuel considered, the vaporization behavior of turbulent sprays may be quite sensitive to the modeling of transient liquid-phase processes. Thus, it is important that for most hydrocarbon fuels these processes be adequately represented in comprehensive spray computations. The present results also provide further support to the conclusions of earlier studies which have been based on simplified spray configurations.