Accession Number : ADA303648

Title :   Reaction Zone Models for Vortex Simulation of Turbulent Combustion.

Descriptive Note : Final rept. 1 Sep 92-31 Aug 95,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Ghoniem, Ahmed F.

PDF Url : ADA303648

Report Date : 27 NOV 1995

Pagination or Media Count : 122

Abstract : The objectives of this work were to develop, implement and validate a reaction zone model for vorticity based turbulent combustion simulation at high Reynolds and Damkohler numbers. Direct Simulation results using the transport element method were used to examine the structure of the reaction zone and to develop a reasonable set of approximations that could be used to simplify the governing equations. The resulting model, adopting a singular expansion philosophy of the flow equations; the elemental flame model consists of (1) a conserved scalar approximation of the outer non-reacting flow to determine the location of the reaction surface; (2) an unsteady, uniformly strained flame structure model for the inner reacting flow imbedded within the reaction surface, to compute the local burning rate and flame structure profiles; and, (3) a set of kinematically based approximations used to monitor the generation, interaction and elimination of flame surface area as it spins around and reaches the tip of the spiral within large vortical structures. Comparisons between these 'large structure simulations' and direct numerical simulation showed that the model could accurately capture the physics of reacting flows and predict flame surface evolution and rate of burning. Future work should be concerned with (a) extending this model by incorporating another approximation at areas of low strains, i.e., inside the large structure where the reaction zones resemble those of stratified reactors, and (b) extending the application of the developed model to three- dimensional flows. (AN)

Descriptors :   *REACTION KINETICS, *TURBULENT FLOW, *VORTICES, *COMBUSTION STABILITY, KINEMATICS, MATHEMATICAL MODELS, ALGORITHMS, COMPUTERIZED SIMULATION, EDDIES(FLUID MECHANICS), STRAIN(MECHANICS), COMPUTATIONAL FLUID DYNAMICS, FLOW FIELDS, APPROXIMATION(MATHEMATICS), MIXING, DIFFUSION, UNSTEADY FLOW, FLAME PROPAGATION, BURNING RATE, NAVIER STOKES EQUATIONS, EXOTHERMIC REACTIONS, REYNOLDS NUMBER, SHEAR FLOW, LAGRANGIAN FUNCTIONS, COMBUSTION PRODUCTS.

Subject Categories : Fluid Mechanics
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE