Large eddy simulation of strut enhanced mixing for supersonic combustion

Large Eddy Simulation (LES) of supersonic combustion in a model scramjet combustor based on an Open Source Field Operation and Manipulation (OpenOAM) computing platform was established, with two different wall boundary conditions, i.e. slip and viscous walls applied. The three-dimensional LES solver, which adopts a Partially Stirred Reactor (PaSR) sub-grid combustion model along with a skeleton 27 steps hydrogen chemical kinetics, was used to study strut-enhanced mixing and combustion. LES results show that mean axial velocity and temperature at different cross sections match well with experimental data, and spatial evolution of the supersonic diffusion flame is well captured. Effects of shear layers growth, development and breaking down on combustion processes were discussed in detail, and the coupling effects with vortex shedding at the strut base were revealed. Different mixing modes were recognized after the strut where subsonic and supersonic flows co-exist. Explosive chemical processes and their characteristic time scales were acquired by the Chemical Explosive Mode Analysis (CEMA) method, and the detailed structure and stabilization mechanism of the flame was identified.