Development of a three dimensional radiative heat transfer computational methodology for aircraft engine combustors

Abstract

A computational methodology for radiative heat transfer analysis in three-dimensional non-gray enclosures is presented in this paper. This methodology which is applicable to aircraft engine combustors includes the non-gray interaction of the multiple gaseous species, H2O, CO2, and CO respectively. It also includes models for luminous radiation from soot. The analysis procedure uses a finite volume methodology (FVM) in body fitted coordinates (BFC) for radiative transfer along with the weighted-sum-ofgray gases (WSGG) concept for treating the non-gray gases. The methodology provides the divergence of radiative heat flux at each cell of the FVM grid for inclusion in the flow solver. It also provides the radiative heat flux and intensity of radiation at each cell. The methodology has been validated by application to a wide variety of test cases. Application to a generic combustor is also made. INTRODUCTION In gas turbine combustion chambers, a large portion of the total heat flux to the liners is by radiation Senior Engineer, Associate Fellow AIAA Aerospace Engineer, Member AIAA Project Engineer; Manager Copyright © 1998 by the American Institute of Aeronautics and Astronautics. from the flame. Hence it is important to include the effects of radiation in the equations solved by the CFD flow solver. The objective of the present methodology is to obtain the divergence of the radiative heat flux term to be included in the energy equation. A finite volume 3-D radiative heat transfer methodology using the generalized curvilinear coordinates (BFC) applicable to combustor flow computations is presented. Absorbing, emitting and anisotropically scattering non-gray media can be modeled in the methodology. Spectrally dependent boundary conditions can also be modeled in the methodology. The methodology accounts for non-gray medium using a procedure that combines the weighted -sum-of-gray-gases (WSGG) concept with narrow band models and the k-distribution method. Interaction of multiple gaseous radiating species are included in the WSGG model for non-gray analysis. The gaseous radiating species currently modeled are H2O, CO2, and CO. N2 and O2 are considered transparent gases in this analysis. The absorption and scattering properties of soot are based on the Rayleigh-Debye-Gans (RDG) scattering approximation while treating the soot as mass-fractal-aggregates of spherical primary particles that have constant diameters and refractive indices. Several test cases were used in validating the methodology. The methodology provides the divergence of radiative heat flux at each cell of the FVM grid for inclusion in the flow solver. It also provides the radiative heat flux and intensity of radiation at each cell. The methodology has been validated by application to a wide variety of test cases. Application to a generic combustor is also performed. 1 American Institute of Aeronautics and Astronautics Copyright© 1997, American Institute of Aeronautics and Astronautics, Inc.