Adaptive simulations of cavity-based detonation in supersonic hydrogen–oxygen mixture

Abstract

Two-dimensional reactive Euler equations with a detailed reaction modelwhere the molar ratio of the combustible mixture H2/O2/Ar is 2:1:7 under the condition of pressure 6.67 kPa and temperature 298 K, are solved numerically with adaptive mesh refinement method to investigate detonation combustion using a hot jet initiation in cavity-based channels filled with the supersonic combustible mixture.Results show that from the comparison between the simulations in a cavity-based channel and a straight channel without any cavity embedded, it is indicated that the cavity can help realize detonation initiation in the combustible mixture with a hot jet.It is suggested that detonation initiation can be realized using a relatively weaker hot jet in cavity-based channels filled with the supersonic combustible mixture compared with that in straight channels without a cavity embedded. The cavity also plays a significant role in detonation propagation in the supersonic combustible mixture.After the hot jet is shut down, the acoustic wave generated by the subsonic combustion in the cavity can accelerate detonation propagation through a subsonic Corresponding author. Email addresses: cai-chonger@hotmail.com, jhleon@vip.sina.com, r.deiterding@soton.ac.uk, linzy96@nudt.edu.cn, channel and result in the formation of a slightly overdriven detonation eventually. For a given flow with a shadow cavity embedded, there should exist a minimum cavity width Lmin. When the width is below Lmin, only some pressure oscillations in the cavity can make some impacts on detonation initiation and propagation. Otherwise, cavity oscillations can be generated which can greatly accelerate detonation initiation and propagation in the supersonic combustible mixture. For the shadow cavity, purely increasing the cavity depth does not have any more influence on detonation combustion. However, if the cavity is a deep one, it can play an important role in accelerating detonation initiation and propagation in the supersonic combustible mixture due to resonant oscillations.

Detonation interaction with cavity in supersonic combustible mixture

“…The Mach detonation reflection, which serves as a strong ignition source, contributes significantly to the realization of a complete detonation initiation in the whole channel. In the previous work [28], when the incoming velocity is given as the CJ velocity, the detonation front is almost sustained at the same location upstream in the cavity after the hot jet is shut down due to cavity oscillation. It is suggested that, for a successful detonation wave interaction with cavity, the incoming flow velocity should be higher than the corresponding CJ velocity to ensure downstream propagation of detonation after the hot jet shutdown.…”

“…The hot jet is set to the equilibrium CJ state of a H 2 ∕O 2 mixture with a stoichiometric molar ratio under the condition of pressure 6.67 kPa and temperature 298 K [28]. To model the sonic injection in experiments, the injection velocity of the jet is set to the local sonic speed to make it a chocked one.…”

“…Because of the outstanding potential to stabilize combustion by cavity oscillations [21][22][23][24][25][26][27], recently detonation combustion has been numerically investigated in cavity-based channels filled with a supersonic hydrogen-oxygen mixture [28]. It is reported that the cavity can help realize detonation initiation and accelerate its propagation in the supersonic combustible mixture due to pressure wave enhancement resulting from subsonic combustion in the cavity.…”

Detonation Interaction with Cavity in Supersonic Combustible Mixture

“…The detailed process of detonation initiation using a hot jet in a cavity-embedded channel has been illustrated previously in detail [28], where the velocity of the supersonic incoming flow is given as the corresponding V CJ . To have a quick understanding of this issue, a very brief introduction is provided here.…”

Experimental and numerical investigations on propagating modes of detonations: Detonation wave/boundary layer interaction

“…In addition, it is expected that the DDS can be suitable for higher flight Mach numbers than the 3 conventional scramjet. Based on this idea, we have conducted a series of numerical simulations [5][6][7][8] on detonation combustion in supersonic combustible mixtures using a hot jet initiation. The adaptive mesh refinement open-source program AMROC (Adaptive Mesh Refinement in Object-oriented C++) [9][10][11] based on the Structured Adaptive Mesh Refinement (SAMR) approach [12][13] had been adopted to solve the reactive Euler equations with simplified [14] and detailed reaction models [15] using a robust second-order accurate MUSCL-TVD scheme.…”