Effect of spatial inhomogeneities on detonation propagation with yielding confinement

Mi, Xiaocheng; Higgins, Andrew; Kiyanda, Charles B.; Ng, Hoi Dick; Nikiforakis, Nikolaos

doi:10.1007/s00193-018-0847-8

Cited by 31 publications

(11 citation statements)

References 53 publications

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“…The use of GPU-accelerated computing platforms has been explored in several studies on gaseous detonations. [48][49][50][51] The current code is a further development of the gaseousdetonation code to simulate detonations in a multiphase energetic system. This code is of a hybrid nature, consisting of parts that are executed on both CPU (Central Processing Unit) and GPU.…”

Section: Numerical Methodologymentioning

confidence: 99%

Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavities

Michael

Ioannou

et al. 2019

Journal of Applied Physics

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Two-dimensional, meso-resolved numerical simulations are performed to investigate the complete shock-to-detonation transition (SDT) process in a mixture of liquid nitromethane (NM) and air-filled, circular cavities. The shock-induced initiation behaviors resulting from the cases with neat NM, NM with an array of regularly spaced cavities, and NM with randomly distributed cavities are examined. For the case with randomly distributed cavities, hundreds of cavities are explicitly resolved in the simulations using a diffuse-interface approach to treat two immiscible fluids and GPUenabled parallel computing. Without invoking any empirically calibrated, phenomenological models, the reaction rate in the simulations is governed by Arrhenius kinetics. For the cases with neat NM, the resulting SDT process features a superdetonation that evolves from a thermal explosion after a delay following the passage of the incident shock wave and eventually catches up with the leading shock front. For the cases wherein mesoscale heterogeneities are explicitly considered, a gradual SDT process is captured. These two distinct initiation behaviors for neat NM and heterogeneous NM mixtures agree with experimental findings. Via examining the global reaction rate of the mixture, a unique time scale characterizing the SDT process, i.e., the overtake time, is measured for each simulation. For an input shock pressure less than approximately 9.4 GPa, the overtake time resulting from a heterogeneous mixture is shorter than that for neat NM. This sensitizing effect is more pronounced for lower input shock pressures. A random distribution of cavities is found to be more effective in enhancing the SDT process than a regular array of cavities. Statistical analysis on the meso-resolved simulation data provides more insights into the mechanism of energy release underlying the SDT process. Possible directions towards a quantitatively better agreement between the experimental and meso-resolved simulation results are discussed. arXiv:1905.05727v2 [physics.comp-ph]

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Section: Numerical Methodologymentioning

confidence: 99%

Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavities

Michael

Ioannou

et al. 2019

Journal of Applied Physics

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“…They found that the spatial heterogeneity enables the detonation wave to propagate at near limit conditions at greater velocities and in thinner layers than the corresponding homogeneous case. Mi et al [18][19][20] studied the effect of spatial discretization of energy on detonation propagation. They found that the average detonation wave speeds in a spatially inhomogeneous reactive medium is significantly greater than the corresponding CJ speed of the homogeneous reactive medium.…”

Section: Introductionmentioning

confidence: 99%

Effects of disturbance on detonation initiation in H2/O2/N2 mixture

et al. 2018

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Detonation initiation has been extensively investigated in the past several decades. In the literature, there are many studies on detonation initiation using a large amount of blast energy and obstacles to respectively achieve direct detonation initiation or deflagration to detonation transition (DDT). However, there are few studies on detonation initiation with a non-uniform initiation zone. In this work, two-dimensional numerical simulations considering detailed chemistry and transport are conducted to investigate the effects of disturbance on detonation initiation in a stoichiometric H2/O2/N2 mixture. The high-pressure and high-temperature detonation initiation regime is imposed by a sinusoidal disturbance. Introduction of such disturbance is found to promote the onset of detonation and to reduce time and distance for detonation formation. This is mainly because such disturbance can induce shock wave interaction, which generates transverse waves. The reflected transverse waves result in local autoignition/explosion. The coherent coupling between local autoignition and pressure wave resulting from a large amount of heat release eventually leads to the detonation development. It is found that the distance and duration for detonation initiation become shorter when a disturbance with smaller wavelength or larger amplitude is enforced. When the ratio between the wavelength and amplitude of disturbance is fixed, the change in wavelength and amplitude has little influence on detonation initiation. Therefore, disturbance with either small wavelength or large amplitude can be used to promote detonation initiation.

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“…The solutions to the above equation systems are obtained numerically using a 2nd order MUSCL-Hancock scheme with an HLLC Riemann solver [67,68], with a CFL number of 0.90. To reduce the simulation run-time, the entire flow solver was implemented using NVIDIA CUDA programming language (NVIDIA Corp., Santa Clara, CA, USA) and run on a NVIDIA Tesla K40 General Purpose Graphics Processing Unit GPGPU [68][69][70]. Application of the GPU-CPU framework improves significantly the computational performance allowing high resolution simulations and parametric study to be performed efficiently.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Chemical Reactivity on the Formation of Gaseous Oblique Detonation Waves

Yan

Teng

et al. 2019

Aerospace

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High-fidelity numerical simulations using a Graphics Processing Unit (GPU)-based solver are performed to investigate oblique detonations induced by a two-dimensional, semi-infinite wedge using an idealized model with the reactive Euler equations coupled with one-step Arrhenius or two-step induction-reaction kinetics. The novelty of this work lies in the analysis of chemical reaction sensitivity (characterized by the activation energy E a and heat release rate constant k R ) on the two types of oblique detonation formation, namely, the abrupt onset with a multi-wave point and a smooth transition with a curved shock. Scenarios with various inflow Mach number regimes M 0 and wedge angles θ are considered. The conditions for these two formation types are described quantitatively by the obtained boundary curves in M 0 -E a and M 0 -k R spaces. At a low M 0 , the critical E a,cr and k R,cr for the transition are essentially independent of the wedge angle. At a high flow Mach number regime with M 0 above approximately 9.0, the boundary curves for the three wedge angles deviate substantially from each other. The overdrive effect induced by the wedge becomes the dominant factor on the transition type. In the limit of large E a , the flow in the vicinity of the initiation region exhibits more complex features. The effects of the features on the unstable oblique detonation surface are discussed.Aerospace 2019, 6, 62 2 of 17 the conditions and interpret the observed flow field regimes in terms of competing reactions and flow-quenching effects.Alternatively, an oblique detonation wave can be induced by a wedge in an incoming reactive flow [20][21][22]. A standing oblique detonation wave attached to the wedge tip presents a more practical configuration for engine operation [23][24][25]. There has been indeed a remarkable progress in understanding the fundamental aspects of oblique detonation waves induced by a semi-infinite, two-dimensional wedge. Analytical solutions such as wave angles and steady structures as the basic foundation were sought in a number of pioneering works using detonation polar analysis by approximating the ODW as an oblique shock wave (OSW) coupled with an instantaneous post-shock heat release [26][27][28][29]. In later studies, it has been demonstrated that the ODW formation structure induced by the wedge is more complex. In many cases, an oblique shock wave first forms upon the flow interaction with the wedge igniting the combustible flow mixture, and subsequently transits into an oblique detonation wave [30]. Due to the strong coupling sensitivity between fluid dynamics and chemical reactions, as well as the inherent unstable nature of detonation waves [31], it remains technically challenging to establish steady oblique detonations in high-speed combustible mixtures for practical propulsion applications, and such success requires fundamental understanding of the initiation structure of oblique detonation waves. To this end, the dynamics of ODW formation has recently drawn significant research attention...

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Effect of spatial inhomogeneities on detonation propagation with yielding confinement

Cited by 31 publications

References 53 publications

Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavities

Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavities

Effects of disturbance on detonation initiation in H2/O2/N2 mixture

The Effect of Chemical Reactivity on the Formation of Gaseous Oblique Detonation Waves

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