Effect of Inflow Turbulence on Premixed Combustion in a Cavity Flameholder
[Technical Report, Memorandum Report]
NAVAL RESEARCH LAB WASHINGTON DC
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A discontinuous Galerkin xCfinite element method code, JENRE, was used to perform highly resolved simulations of ramjet-mode combustion in the University of Virginia Supersonic Combustion Facility cavity flame holder at a high enthalpy of Mach 5. The primary goal of the work is to enhance our understanding of the effects of turbulence on fully premixed ramjet combustion with a hydrocarbon fuel. Prior experiments measured a freestream turbulence intensity at the inflow to the cavity ranging from 10 15 . A synthetic turbulence inflow generator was implemented for the simulations in this work to reproduce the turbulence at the inflow to the cavity. This reduced computational expense, as the turbulent, non-reacting flow upstream of the cavity was generated by a boundary condition rather than requiring the modeling of the entire upstream domain. Velocity perturbations and turbulence intensity generated by the turbulent inflow boundary condition are shown to match those values measured in the facility using particle induced velocimetry. Simulations were performed both with and without inflow turbulence to study the effect of turbulence on flame stability and structure. In both cases, a cavity-stabilized flame was achieved. The inflow turbulence promoted more robust combustion, causing the me to propagate further from the cavity into the core ow, broadening the flam angle with respect to the axial ow direction.
- Combustion and Ignition