The role of cellular instability on the critical tube diameter problem for unstable gaseous detonations

Han, Xu; Mi, Xiaocheng; Kiyanda, Charles B.; Ng, Hoi Dick; Lee, John H. S.; Yao, Chunde

doi:10.1016/j.proci.2018.05.133

Cited by 19 publications

(12 citation statements)

References 25 publications

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“…In the seminal work by Vasil'ev 13 , re-initiation of a subcritical diffraction wave could be promoted via its reflection on a localized obstacle near the expanding cone in the open area. Following the same line of work, Xu et al 1,2 in their experiments inserted a relatively smaller obstacle to promote the generation of transverse waves and to demonstrate the importance of the cellular instabilities at the diffracting front on the re-initiation, see Fig. 2.…”

Section: And Latermentioning

confidence: 89%

“…Using high-speed schlieren photography 1,2 and advanced laser-based diagnostics 15 , recent studies revealed more information on the detailed flow features during the diffraction of detonation waves. At the critical regime, successful transmission of a diffracting detonation wave requires a sufficient degree of cellular instability in the quasi-steady, weakly decoupled reaction-shock complex.…”

Section: And Latermentioning

confidence: 99%

“…The diffraction process and formation of the explosion bubble at the critical condition with po = 6.5 kPa. Note that these photographs were obtained from the experiments reported by Xu et al 1,2 .…”

Section: Figmentioning

confidence: 99%

“…Schlieren images showing a) the subcritical case of transition with po = 5.7 kPa and the effect of perturbation with b) po = 5.0 kPa at 36.5 mm; and c) po = 3.8 kPa at 26.5 mm. Note that these photographs were obtained from the experiments reported by Xu et al 1,2 .…”

Section: Figmentioning

confidence: 99%

“…The phenomenon of detonation diffraction has long been investigated since it provides a platform for investigating both propagation and initiation mechanisms of gaseous detonations. [1][2][3][4] The critical condition for successful transmission has been measured in many studies and generally characterized by the dimension of the channel exit scaled by λ, the intrinsic detonation cell size (e.g., for common unstable hydrocarbon mixtures, the critical channel diameter is given by dc = 13λ) [5][6][7][8][9][10] . The recent experimental study by Nagura et al 11…”

Section: Introductionmentioning

confidence: 99%

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Computational study of gaseous cellular detonation diffraction and re-initiation by small obstacle induced perturbations

et al. 2021

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A gaseous detonation wave that emerges from a channel into an unconfined space is known as detonation diffraction. If the dimension of the channel exit is below some critical value, the incident detonation fails to re-initiate (i.e., transmit into a self-sustained detonation propagating) in the unconfined area. In a previous study, Xu et al. ["The role of cellular instability on the critical tube diameter problem for unstable gaseous detonations," Proc. Combust. Inst. 37, 3545-3533 (2019)] experimentally demonstrated that, for an unstable detonable mixture (i.e., stoichiometric acetyleneoxygen), a small obstacle inserted in the unconfined space near the channel exit promotes the reinitiation capability for the cases with a sub-critical channel size. In the current study, numerical simulations based on the two-dimensional, reactive Euler equations were performed to reveal this obstacle-triggered re-initiation process in greater detail. Parametric studies were carried out to examine the influence of obstacle position on the re-initiation capability. The results show that a collision between a triple-point wave complex at the diffracting shock front and the obstacle is required for a successful re-initiation. If an obstacle is placed too close or too far away from the channel exit, the diffracting detonation cannot be re-initiated. Since shot-to-shot variation in the cellular wave structure of the incident detonation results in different triple-point trajectories in the unconfined space, for an obstacle at a fixed position, the occurrence of re-initiation is of a stochastic nature. The findings of this study highlight that flow instability generated by a local perturbation is effective in enhancing the reinitiation capability of a diffracting cellular detonation wave in an unstable mixture.

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Section: And Latermentioning

confidence: 89%