CRAFT Tech’s Dr. Vineet Ahuja is part of the executive steering committee that is organizing the 2019 AIAA Propulsion and Energy Forum at Indianapolis Indiana from August 19th to 22nd. Also, Dr. Balaji Muralidharan will be presenting in the High Fidelity Combustion Modeling session.
This paper presents an extension to the Flamelet Generated Manifold (FGM) approach to multiphase combustion. The two primary aspects of the extension of the FGM formulation to handle spray evaporation and combustion are (i) the characterization of gas-phase fuel formation and (ii) the need to account for non-adiabatic heat losses due to spray evaporation and droplet heat transfer. To address the first aspect, a source term due to spray evaporation is added to the mixture fraction transport equation. Also, a new approach to define the gaseous fuel stream boundary condition for the FGM table generation is proposed. With regard to the second aspect, volumetric heat losses, e.g., due to the latent heat of vaporization of the spray, are accounted by solving the full compressible governing equations, where the energy equation includes the heat loss source terms. To account for the effects of heat loss on the flame structure, FGM tables are parameterized at different specified values of heat loss or inflow temperature of the oxidizer stream. As a result, the FGM table lookup dimensionality is extended to include the local temperature as an additional search key. Baseline validations of the multiphase FGM extension with heat loss are presented. The flame and spray behavior are then compared using the multiphase FGM and detailed chemistry for a methane spray combustion problem. An overall good agreement between the multiphase FGM and the detailed chemistry is observed. Different approaches to parametrize the heat loss for the FGM table generation are also discussed.