Molecular gas radiation in a laminar or turbulent pipe flow
Abstract
The temperature profile and the radiative and convective wallheat fluxes for a hydrodynamically established flow of a nongray gas in a cylinder are calculated numerically for laminar or turbulent flow. Turbulent eddy viscosity is represented by a tworegion model having a nearwallregion and a farfromwall region. Gas properties are represented by the exponentialwinged band model. The controlling parameters are the ratio of radiation conductance to molecular conductance (Nrm), the maximum spectral optical depth of the radius for the ith gas band, and the turbulent Reynolds number (Rt). Qualitatively the results for a gas with a single major band agree with a previous solution for a cylinder with internal heat generation. Radiative Nusselt number Nu(R) increases nearly linearly with Nrm. Radiative flux increases with optical depth of the tube radius at maximum absorption rapidly at first and then only slowly. Increasing Rt increases markedly the convective Nusselt number and appreciably Nu(R). The gas layer effective transmissivity was found to increase with increasing Rt and decrease with increasing optical depth of the tube radius at maximum absorption.
 Publication:

ASME Journal of Heat Transfer
 Pub Date:
 February 1976
 Bibcode:
 1976ATJHT..98..101W
 Keywords:

 Convective Heat Transfer;
 Laminar Flow;
 Nongray Gas;
 Pipe Flow;
 Radiative Heat Transfer;
 Turbulent Flow;
 Eddy Viscosity;
 Heat Flux;
 Molecular Gases;
 Nusselt Number;
 Reynolds Number;
 Temperature Distribution;
 Fluid Mechanics and Heat Transfer