Evolution of the ignition and combustion process at high velocity at the channel entrance

The article deals with the non-stationary self-ignition of the non-prepared in hydrogen-air mixture in supersonic flow for understanding the influence of the inlet flow velocity on the ignition mode. A series of experiments was carried out at significant change in the inlet velocity into the model channel at the identical flow parameter and equivalence ratio. At the velocity increase, the ignition region shifts downstream due to the change in the wave structure of the flow. Simultaneously, the significant increase of the propagation time of the flame front over the channel occurs that results in the growth of time to reach the stationary combustion regime. It is shown that a flame flashback is a necessary condition for the implementation of combustion at the supersonic flow velocity in the channel, regardless of the inlet velocity. Under identical inlet condition the increase of the Mach number leads to an acceleration of the transition to the subsonic combustion and channel choking. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.