Performance characteristics of methanol and kerosene fuelled meso-scale heat-recirculating combustors

A meso-scale heat recirculating combustor has been developed for the combustion of methanol and kerosene fuels with oxygen enriched superheated steam as an oxidizer. The steam oxygen mixture is a surrogate for the decomposition products of hydrogen peroxide, and as such the combustor development is toward meso-scale bi-propellant propulsion. Both the extinction behavior and thermal performances have been examined under partially-premixed and non-premixed configurations of a unique design incorporating heat recirculation. Stable combustion with thermal efficiencies of ∼90% has been demonstrated with both methanol and kerosene. Global flame behavior is investigated through direct image photography of the flame that revealed different flame modes at various equivalence ratios (Φ), including “flameless” combustion of kerosene. Density impulse values calculated based on exhaust temperatures and simulated equilibrium gas properties and assuming 1 atm chamber pressure and expansion to vacuum show that the maximum density impulse of kerosene/steam/oxygen combustion to be within 6% of the adiabatic density impulse of hydrazine/nitrogen tetroxide.