Analysis and Closure of Dissipation Rates in a Physically Derived Reduced-Order Manifold for Turbulent Combustion

Abstract

A physically derived reduced-order manifold for turbulent combustion modeling has been proposed, with the capability of providing both low computational cost and generality to multiple modes of combustion. The manifold uses two coordinates, mixture fraction and a generalized progress variable. The work in this thesis seeks to understand and model the effects of dissipation rates of these coordinates in the manifold. Reacting flow simulations of a lifted coflow flame are performed as a reference case. Manifold coordinates and corresponding dissipation rates are calculated from the simulation data. The dissipation rate profiles from the simulation are compared to existing models for the dissipation rates in the manifold. The mixture fraction dissipation rate and progress variable dissipation rate are shown to be well approximated by the existing models. A potential model is proposed for the alignment used in the cross-term dissipation rate. Accordingly, closure is achieved for the three dissipation rates in the manifold.