Turbulent Combustion Study of Scramjet Problem
Research Foundation of SUNY at Stony Brook Stony Brook United States
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In this thesis we study the turbulent mixing and turbulent combustion in a model scramjet combustor with a Large Eddy Simulation LES strategy. LES resolves the large and energetic motions while the small subscale motions are modeled. Here the filtered Navier-Stokes equations are solved by a fifth-order finite difference Weighted-Essentially Non-Oscillatory WENO scheme dimension by dimension. The subgrid terms are closed by the dynamic Smagorinsky model. The chemical source terms are calculated directly using a finite rate chemistry model with a reduced chemical mechanism. The turbulent boundary layer model of J. Larsson is used to calculate the shear stress and heat flux at the wall. The inflow turbulent is generated by the digital filtering method. The main result is a methodology to predict the mesh convergence for three-dimensional turbulent combustion simulation, based on a less expensive suite of one-dimensional and two-dimensional simulations. We first determine the grid requirements for finite rate chemistry with detailed mechanism and reduced chemical mechanism respectively in the context of one-dimensional simulations. These criteria are verified through simulation in a two-dimensional context and refined with corrections due to turbulent transport. They are then applied to three-dimensional simulations. A grid sensitivity study of the turbulent boundary layer is conducted in a 2D context. Simulation results are validated through comparison with a simulation of the same problem conducted by J. Larsson, using a different methodology and by comparison to experiments performed at Stanford University.
- Fluid Mechanics
- Combustion and Ignition
- Jet and Gas Turbine Engines