Numerical Exploration of the Flame Regimes in a Mach 7 Axisymmetric Combustor Experiment

High-fidelity simulations are used to explore the range of flame regimes that occur in a generic, axisymmetric supersonic combustion duct that was designed to operate at nominally Mach 7 flight enthalpy conditions. A set of three different conditions of the combustor flowpath were simulated numerically. Different burning modes were established in each case by altering the injection splitting which resulted in a mixed, partially supersonic/partially subsonic burning mode of the combustor, a predominantly supersonic burning mode, and a predominantly subsonic burning mode. The topology of the averaged and instantaneous flame front in each mode is described as well and its relation to overall properties of the established flowfields. A statistical description of the flames shows the variation in the distribution of premixed versus non-premixed burning that occurs in each case as well as the variation in supersonic versus subsonic burning.