Step Geometry and Countercurrent Effects in Dump Combustor: Reacting Flow

Abstract

In this article we report a numerical investigation of reacting flow in dump combustors with counterflow and modified step geometry. The flow is simulated by solving Reynolds-averaged Navier-Stokes equations in the framework of the realizable κ–∊ turbulence model. A two-layer approach is used for the near-wall treatment, whereas a one-equation model is employed for the viscous sublayer. The closure for the reaction source term is based on the eddy dissipation concept. The article includes a study of the effect of reaction on the base flow, the effect of countercurrent on the flame, and finally, the role of step geometry. Application of countercurrent results in a thicker averaged flame surface, which leads to an overall increase in the heat release within the combustor. The effect of alteration of the step geometry is found to be much more complicated. At low levels of counterflow there is an increase in turbulence intensity with an increase of the step angle but little change in heat release.

Support for this work was provided by the U.S. Office of Naval Research with Dr. G. D. Roy as the Program Officer. The authors thank Dr. P. J. Strykowski for useful discussions on the physics of countercurrent shear.