Interaction between chemical reaction and turbulence in nonpremixed H sub 2 -air combustion
Two prediction models for a turbulent axisymmetric diffusion flame for H2-Air combustion are presented for supersonic jet flows. In the first code, Code I, the parabolic transport equations describing the velocity and scalar fields are solved by a marching downstream integration procedure. For the second code, Code II, the complete time-averaged 2-D Navier-Stokes equations and the species transport equations are solved in a fully-coupled and implicit manner. The modeled moment transport equations are expressed in Favre form and closure to these equations is done with a gradient-type closure approach. Both equilibrium and nonequilibrium chemistry models are incorporated in Code I. In the finite chemistry analysis, the fast shuffle reactions in the H2-Air reaction system are assumed to be in partial equilibrium and three-body recombination reactions are treated kinetically. The combustion processes for Code II are modeled by an 8-species, 18-step finite rate chemistry model. The turbulence is simulated by Eggers algebraic model. The program employs an implicit finite volume, lower-upper symmetric successive overrelaxation scheme (LU - SSOR) for solving the finite difference equations. The model predictions obtained from Codes I and II are compared to probe measurements in a supersonic H2-Air jet flame by Beach. Comparison of the mixture fracture deduced from Beach's data to the model indicate that for Code I the turbulent transport process is correctly predicted, whereas the numerical results for the mixture fraction profiles of Code II compare poorly with the measurements. The turbulence characteristics of the flow have a significant effect on chemical reaction.
- OSTI ID:
- 5925393
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
083000* -- Hydrogen-- Combustion-- (1990-)
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION KINETICS
COMPUTER CODES
DIFFERENTIAL EQUATIONS
DIFFUSION
ELEMENTS
EQUATIONS
FINITE DIFFERENCE METHOD
FLAMES
FLUID FLOW
HYDROGEN
ITERATIVE METHODS
KINETICS
MATHEMATICAL MODELS
NAVIER-STOKES EQUATIONS
NONMETALS
NUMERICAL SOLUTION
PARTIAL DIFFERENTIAL EQUATIONS
REACTION KINETICS
RECOMBINATION
SUPERSONIC FLOW
TURBULENT FLOW
TWO-DIMENSIONAL CALCULATIONS