NUMERICAL ANALYSIS OF DIFFUSION AND CONVECTION HEAT AND MASS TRANSFER PROCESSES AT THE MOVING OF WATER DROPS THROUGH HIGH COMBUSTION PRODUCTS

Heat and mass transfer model is presented in article. This model describes main interrelated processes (thermal conductivity, diffusion, convection, evaporation) at the moving of sprayed water single drop through the high-temperature combustion products. Numerical evaluation of the deviations for integral characteristics of the evaporation process, derived with using of diffusion approach, which ignores the formation of convective flows in the emerging mixture of combustion products and water vapor, is carried out. It is shown that the life time of drop
d differ by no more than 4 %. It is found that with increasing droplet sizes deviations
d reduced to 2 %. Also validity of diffusion models using in numerical investigation of heat and mass transfer processes in the wake of drops is analyzed. It is found that the removal of drops at a distance corresponding to several tens of characteristic longitudinal sizes, convection leads to some (to 15–20 %) reduction in the longitudinal and transverse dimensions of “temperature” and “concentration” tracks — areas with lower values of the temperature of the combustion products relative to the start and their concentrations. It is shown that in these conditions it is advisable to use models that include convective and diffusion mechanisms of mass transfer.