Efficient Three-Dimensional CFD Model for Spray Combustion

A program is proposed to demonstrate the feasibility of developing a general computational fluid dynamics (CFD) method for predicting turbulent, multi-phase mixing and reacting fluid/particle dynamics for three-dimensional spray combustion systems. The method allows coupled flow, chemistry and polydisperse aerosol behavior to be calculated efficiently in a Eulerian reference frame. Dispersed droplet properties such as size distribution, mass loadings, and interphase energy and mass transfer are solved without having to sum the contributions of individual particle trajectories over the entire particle spectrum as is required in traditional Lagrangian approaches. The method consists of the Full Navier-Stokes (FNS) system of equations based on the Reduced Navier-Stokes (RNS) formulation, coupled with a lognormally distributed, polydisperse moment model for droplet transport (convection, inertia, thermophoresis, buoyancy, and Brownian/turbulent diffusion) and dynamics (nucleation, condensation/evaporation and coagulation). A research code including many of these features has been tested for a variety of inlet, duct, airfoil, cascade, nozzle and plume problems with strong coupling between gaseous and liquid/solid phases. The code can be run quickly and efficiently on PCS and workstations and, therefore, will be effective for detailed parametric studies involving large numbers of cases. The method will be extended to model spray combustion.