Initiation of detonation in flows of fuel-air mixtures

Abstract

Regimes of self-ignition of the fuel mixture obtained by controlled separate injection of hydrogen and air into a plane-radial vortex chamber with a rapid (0.2 msec) transition to detonation have been realized for the first time. Self-ignition occurs in the stoichiometric region with a slightly higher (up to 6-30%) content of hydrogen and, normally, in a subsonic flow. The energy of guaranteed detonation initiation is determined for combustors of different geometries and different ratios of fuel components by using a thermal pulse produced by blasting a wire by electric current. Detonation initiation is ensured by using energy of 0.1 J. It is found that the main contribution of energy into the flow of the mixture occurs at the stage of evaporation (ionization) of copper of the blasted wire. The continuous spin detonation regime is found to decay as the exit cross section of the combustor is reduced. In the regime of combustion, both detonation and conventional turbulent combustion, the pressure at the periphery of the plane-radial vortex chamber is lower and the pressure at the edge of the exit orifice is higher than that in the case of exhaustion of cold fuel components.

Rotating Detonation Wave Propulsion: Experimental Challenges, Modeling, and Engine Concepts

“…Although some earlier work assumed the engine may be connected to a converging-diverging nozzle, 60 convergence at the end of the annular combustor may in fact be detrimental to the RDE. Bykovskii et al 61 note that an increase in the chamber pressure as a result of smaller outflow through the contraction will prevent the inflow of fresh reactants.…”

Survey of Rotating Detonation Wave Combustor Technology and Potential Rocket Vehicle Applications

“…Detonation cell size for hydrogen and methane fuels in a pure oxygen environment relative to the initial gas pressure. 17 These data are extrapolated using the power laws shown to pressures representative of a rocket combustor. dynamic pressure entering the combustion chamber.…”

“…Nevertheless, test data indicate that RDE performance can be sensitive to these parameters. [15][16][17][18] Given these findings, optimum geometry and sizing parameters should exist for any given RDE configuration. A method for deriving these optimal parameters remains somewhat nebulous.…”

“…Existing guidelines generally have a fair amount of uncertainty and are based almost exclusively on empirical test data. [15][16][17][18] …”