Flamelet/Progress-Variable Model for Large eddy Simulation of Supersonic Reacting Flow

The Flamelet/progress variable model for large eddy simulation of supersonic turbulent reacting flows is developed in the present work. Instead of solving transport equations for all of the species in a typical chemical mechanism and modeling the unclosed chemical source terms, the present model only solves two scalar transport equations. One conserved scalar is mixture fraction, which tracks the mixing of fuel and oxidizer, another non-conserved scalar is reactive progress variable, which accounts for chemical variable in directions perpendicular to its gradient. The strong point of the model is its ability to account for ignition and extinction phenomena. Instead of using the steady burning branch in classical steady flamelet model, the present model uses three solution branches: the steady burning branch, the unstable branch of partially extinguished states and the complete extinction state. The performance of the FPV model is compared to the steady flamelet model for predicting species concentration, and temperature filed in a hydrogen-air supersonic combustion scramjet engine for which experimental data are available. The present model is able to obtain good agreement with the experimental data, and to capture extinction and outperform the steady flamelet model which predicts an attached flame. I. Introduction During the last decade a renewed interest in hypersonic air breathing propulsion systems has resulted in an increasing research effort in the field of high speed turbulent combustion. A main focus in recent research activities modeling turbulent combustion has been the complex interactions of the turbulent flow field with the chemical reactions. For the prediction of these interactions, the most frequently used models are the transported probability density function