Augmentor Ignition/Extinction Modeling

The technical objective of this program is to develop a fast running, subgrid scale turbulence-chemistry interaction model for large-eddy simulation (LES) of aircraft augmentors that can accurately capture extinction and ignition effects. To accurately capture extinction and ignition, this model will be based upon a parameterization of the linear-eddy model (LEM). The LEM is a comprehensive mixing model that separately treats molecular diffusion, small scale turbulent stirring and complex, finite-rate kinetics. Because the model resolves the microscale flame structure, extinction and ignition may be accurately captured. Under this program, statistics from this mixing model will be parameterized to form a computationally inexpensive run time model. This parameterization will be accomplished using the artificial neural network (ANN) data modeling technique. The resulting computational model will be a fast running ANN network to estimate the LES filtered reaction rate required by CFD flow solvers. The key advantage of this LEM based ANN modeling approach is that the filtered reaction rate will include within it the effects of subgrid diffusion, turbulent stirring by a range of eddies below the grid size and the response of the chemical composition to these effects.