Accession Number : ADA337370

Title :   Turbulence-Chemistry Models in Highly Strained Non-Premixed Flames

Descriptive Note : Final rept. 1 Sep 94-30 Nov 97

Corporate Author : GENERAL ELECTRIC CORPORATE RESEARCH ANDDEVELOPMENT SCHENECTADY NY

Personal Author(s) : Correa, Sanjay M. ; Hu, Iris Z.

PDF Url : ADA337370

Report Date : 30 JAN 1998

Pagination or Media Count : 64

Abstract : To allow implementation of chemical kinetic schemes of arbitrary complexity in computational design codes for gas-turbine combustion, a new microstructural turbulent combustion model was developed. The fine structure of turbulent combustion was represented by PSR (Perfectly Stirred Reactor) theory. The theory is the intense-combustion analog of flamelet theory. Residence times in the PSR were related to the scalar dissipation, and turbulence-chemistry interactions were closed by using the probability distribution function for scalar dissipation in a turbulent flow. Calculations compared very favorably with Raman data on temperature and species from three turbulent bluff-body stabilized laboratory flames: (i) a non-premixed CO/H2/N2-air flame, (ii) a non-premixed CH4/H2-air flame, and (iii) a premixed CH4-air flame. With this success, the model was applied to two practical combustors: (iv) an axially-staged combustion system which produces about half the NOx of a conventional combustor while offering greater operability, and operates in an unusual regime of turbulence-chemistry interactions, and (v) a conventional aircraft engine combustor. In the latter case, a kinetic scheme with over 121 species and 996 elementary reactions was demonstrated. In both cases, the calculated results agreed well with temperature and species data. The physical model developed here was used directly in the industry-standard pressure-corrected mean Navier-Stokes/assumed-shape pdf/k-epsilon type of CFD code, which affords significant geometric flexibility and rapid convergence for gas-turbine combustor flowfields.

Descriptors :   *AIRCRAFT ENGINES, *TURBULENT FLOW, *STRAIN(MECHANICS), *COMPUTATIONAL FLUID DYNAMICS, *COMBUSTION, *CHEMICAL REACTIONS, TEMPERATURE, COMPUTATIONS, ENGINE COMPONENTS, REACTION KINETICS, AIR, PROBABILITY DISTRIBUTION FUNCTIONS, DISSIPATION, CARBON, NITROGEN, HYDROGEN, OXYGEN, COMBUSTORS, FUELS, GAS TURBINES, PROPULSION SYSTEMS, FLOW FIELDS, CONVERGENCE, KINETICS, SCALAR FUNCTIONS, FLAMES, METHANE, RAMAN SPECTRA.

Subject Categories : Physical Chemistry
      Fluid Mechanics
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE