Detonation attenuation and re-initiation in expanding channels

Abstract

Two-dimensional adaptive simulations are carried out solving the reactive Euler
equations with a detailed reaction model based on the open-source program AMROC to investigate detonation evolution using a hot jet initiation in expanding channel filled with supersonic combustible mixtures. The results show that the supersonic mixture experiences a Prandtl-Meyer expansion with according flow acceleration in the expanding channel, which eventually leads to the nonuniformity of the incoming flow. The nonuniformity characteristic of the mixture results in the generation of a curved detonation directly behind the expansion region. Due to the low numerical diffusion for high grid-resolution, the unburned jet directly behind the expansion fan is consumed slowly, hence resulting in some chemical heat loss when it is released after the sonic plane behind the detonation front. This can further weaken the detonation front, which might be one of the reasons that result in the rapid attenuation of the detonation front. Because of highly oscillating near the upper wall resulting from the expansion fan, the shear layer along with the unburned jet becomes very unstable, hence leading to unsuccessful construction of hydrodynamic throat. As a result, the detonation cannot sustain but continuously attenuate, and finally fails, which is expected to realize re-initiation utilizing the hot jet injection once again before the shock front is totally blew out of the channel.

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Identifiers

ORCID for Ralf Deiterding: orcid.org/0000-0003-4776-8183

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