Onset of detonation in hydrogen-air mixtures due to shock wave reflection inside a combustion chamber

Abstract

Hydrogen fuel, as for now, is the most energy efficient and clean fuel for aviation engines. At present time RAM engines based on chemical burning of fuels and accelerating exhaust gases practically reached the top of their efficiency in terms of specific impulse. New schemes are under development. As it is known, complex geometry of combustion chambers could bring to compression waves focusing and changing the mode of flame propagation from slow combustion to detonation. Keeping this process under control is of major importance for developing new generation of engines. The paper presents results of numerical and experimental investigation of mixture ignition and detonation onset in shock wave reflected from inside a wedge. Comparison of numerical and experimental results made it possible to validate the developed 3-D transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen – air mixtures. Kinetic schemes were improved based on comparison of numerical and experimental results. A tool was developed making it possible to set a criterion for obtaining either safe combustion regime, or transition to detonation regime in shock wave focusing.