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LES/RANS Simulation of a Supersonic Reacting Wall Jet

Abstract

This work presents results from large-eddy / Reynolds-averaged Navier-Stokes (LES/RANS) simulations of the well-known Burrows-Kurkov supersonic reacting wall-jet experiment. Generally good agreement with experimental mole fraction, stagnation temperature, and Pitot pressure profiles is obtained for non-reactive mixing of the hydrogen jet with a non-vitiated air stream. A lifted flame, stabilized between 10 and 22 cm downstream of the hydrogen jet, is formed for hydrogen injected into a vitiated air stream. Flame stabilization occurs closer to the hydrogen injection location when a three-dimensional combustor geometry (with boundary layer development resolved on all walls) is considered. Volumetric expansion of the reactive shear layer is accompanied by the formation of large eddies which interact strongly with the reaction zone. Time averaged predictions of the reaction zone structure show an under-prediction of the peak water concentration and stagnation temperature, relative to experimental data and to results from a Reynolds-averaged Navier-Stokes calculation. If the experimental data can be considered as being accurate, this result indicates that the present LES/RANS method does not correctly capture the cascade of turbulence scales that should be resolvable on the present mesh. Instead, energy is concentrated in the very largest scales, which provide an over-mixing effect that excessively cools and strains the flame. Predictions improve with the use of a low-dissipation version of the baseline piecewise parabolic advection scheme, which captures the formation of smaller-scale structures superimposed on larger structures of the order of the shear-layer width

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