Characteristics of Hypersonic Mach 5 Turbulent Reacting Flow*

Premixed hydrogen and air mixtures were used to create a combustible supersonic flow in a hypersonic combustor facility. The Mach 5 mixture was driven by an axis-symmetric square converging-diverging nozzle. The stagnation pressure and equivalence ratio of the premixed flow is varied. The flow was ignited through use of a miniaturized detonation tube (predetonator). High-speed schlieren, high-speed OH chemiluminescence, and pressure transducers capture the evolution of the supersonic reacting flow. Testing showed differences in the propagation of the shock-induced supersonic combustion at different operating regimes. At lean conditions, the leading shock and flame front decoupled. At higher equivalence ratios (above 0.70), shocks propagated upstream into the nozzle followed by a sustained supersonic reacting flow. At high stagnation pressure regimes, multiple modes of reacting supersonic flows were observed.