Title: Joint effects of geometry confinement and swirling inflow on turbulent mixing in model combustors: a second-moment closure study

Authors: S. Jakirlic, R. Jester-Zurker, C. Tropea

Addresses: Chair of Fluid Mechanics and Aerodynamics, Darmstadt University of Technology, Petersenstr. 30, D-64287 Darmstadt, Germany. ' Chair of Fluid Mechanics and Aerodynamics, Darmstadt University of Technology, Petersenstr. 30, D-64287 Darmstadt, Germany. ' Chair of Fluid Mechanics and Aerodynamics, Darmstadt University of Technology, Petersenstr. 30, D-64287 Darmstadt, Germany

Abstract: An isothermal, incompressible, swirling flow in three generic combustor configurations featuring different inflow structure with respect to the circumferential velocity type (both configurations with annular and central swirling jet were considered), combustor confinement (in terms of expansion ratio ER) and swirl intensity (S) was studied computationally by means of Reynolds Averaged Navier-Stokes method (RANS), using second-Moment Closure (SMC) models. The work focuses on the investigation of the combined effects of the above-mentioned flow parameters on the mixing between a swirling annular jet (representing air stream) and the non-swirling inner jet (representing fuel) within a combustor. Both the basic high-Reynolds number SMC model, modified to account for the non-linearities in the pressure scrambling and dissipation processes, and a low-Reynolds number SMC model, accounting separately for the viscous and non-viscous wall blockage, were applied. Inflow conditions are computationally generated, rather than prescribed. In the course of the inflow data generation, a number of the ||equilibrium|| swirling flows in the concentric annulus and pipe geometries, from which coaxial and central swirling jets expand into a combustion chamber, are computed. The SMC results reproduced all important mean flow and turbulent features in good agreement with available experimental and LES data.

Keywords: model combustor; swirling flow; turbulent mixing; turbulence; scalar transport models; second-moment closure level.

DOI: 10.1504/PCFD.2004.004088

Progress in Computational Fluid Dynamics, An International Journal, 2004 Vol.4 No.3/4/5, pp.198 - 207

Published online: 29 Mar 2004 *

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