Numerical simulation of detonation initiation and propagation in supersonic combustible mixtures with non-uniform species

Abstract

Adaptive high-resolution simulations of gaseous detonation using a hot jet initiation were conducted in supersonic combustible mixtures with spatially non-uniform species. The two-dimensional Euler equations were used as the governing equations in combination with a detailed hydrogen-oxygen reaction model. Three different groups of mixtures, which represent various degrees of chemical reactivity, were investigated. The results show that when the mixtures generally have a high degree of chemical reactivity, detonation initiation can eventually be realized successfully by Mach reflection as well as the DDT mechanism, independent of the spatial distribution of the mixture in the channel. A recurring four-stage sequence of detonation initiation, detonation attenuation, initiation failure and detonation reinitiation can be identified. When the mixtures generally have an intermediate degree of chemical reactivity, detonation combustion can be fully realized in the channel, where different degrees of overdrive are found in the upper lower half. After the shutdown of the hot jet, the overdriven detonation attenuates gradually and eventually a slightly overdriven detonation and a slightly underdriven detonation are generated, which can be regarded as a new stable state of propagation. However, whether a detonation can be initiated successfully is determined by the spatial mixture distribution. In mixtures with low degree of chemical reactivity, detonation initiation can generally not be realized. In this case, successful realization of detonation initiation should be realizable by using of a stronger hot jet.

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

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