An investigation of the shock initiation of liquid nitromethane

Hardesty, D.R.

doi:10.1016/0010-2180(76)90026-2

Cited by 66 publications

(44 citation statements)

References 23 publications

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“…Arrows note where deviation from the unreacted universal liquid Hugoniot reference curve (shown in black) occurs, except for nitromethane, where no Hugoniot points have been reported above the reaction conditions, but reaction has been observed at the blue arrow at an induction time of ~200 ns. 13 These data appear to indicate that reactions require higher shock stress to occur within the time window of the shorter time measurements.…”

Section: Experimental Methodsmentioning

confidence: 88%

“…The shock is only supported for 300 ps, and all measurements are made during this time window. Figure 1 illustrates Hugoniot data for acrylonitrile, phenylacetylene, nitromethane, and carbon disulfide measured with plate impact data [8][9][10][11][12][13][14][15] recorded on nanosecond to microsecond time scales along with laser driven shock data measured on picosecond time scales. 4,5,16 The arrows mark the onset of deviation of the Hugoniot from the universal liquid Hugoniot along the particle velocity axis.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

McGrane

Brown

Bolme

et al. 2017

AIP Conference Proceedings

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Abstract. Chemistry occurring on picosecond timescales can be observed through ultrafast laser shock drive experiments that measure Hugoniot data and transient absorption. The shock stress needed to induce chemical reactions on picosecond time scales is significantly larger than the stress needed to induce reactions on nanosecond time scales typical of gas gun and explosively driven plate impact experiments. This discrepancy is consistent with the explanation that increased shock stress leads to increased temperature, which drives thermally activated processes at a faster rate. While the data are qualitatively consistent with the interpretation of thermally dominated reactions, they are not a critical test of this interpretation. In this paper, we review data from several shocked liquids that illustrate a Hugoniot cusp due to volume changing reactions that occurs at higher shock stress states in picosecond experiments than in nanosecond to microsecond experiments. We also correlate the observed Hugoniot cusp states with transient absorption changes that occur due to the buildup of reaction products.

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Section: Experimental Methodsmentioning

confidence: 88%

Section: Experimental Methodsmentioning

confidence: 99%

Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

McGrane

Brown

Bolme

et al. 2017

AIP Conference Proceedings

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“…Many sets of the reaction rate parameters are available in the literature for liquid nitromethane. For example, (C, T A ) = (2.6 × 10 9 s −1 , 11,500 K) is suggested by Hardesty [14], (6.9 × 10 10 s −1 , 14,400 K) is used by Tarver and Urtiew [15] and (1.27 × 10 12 s −1 , 20,110 K) is used by Ripley et al [16]. In this work, we adopt the pre-exponential factor proposed by Hardesty [14] and adjust the activation temperature to T A = 11,350 K to match the experimentally calculated overtake time and the shape of the velocity versus distance graph of the shock-induced ignition experiment in Sheffield et al [17] (neat nitromethane, shocked at 9.1 GPa).…”

Section: Reaction Rates For Nitromethanementioning

confidence: 99%

“…For example, (C, T A ) = (2.6 × 10 9 s −1 , 11,500 K) is suggested by Hardesty [14], (6.9 × 10 10 s −1 , 14,400 K) is used by Tarver and Urtiew [15] and (1.27 × 10 12 s −1 , 20,110 K) is used by Ripley et al [16]. In this work, we adopt the pre-exponential factor proposed by Hardesty [14] and adjust the activation temperature to T A = 11,350 K to match the experimentally calculated overtake time and the shape of the velocity versus distance graph of the shock-induced ignition experiment in Sheffield et al [17] (neat nitromethane, shocked at 9.1 GPa). It should be noted that even though the single-step Arrhenius rate equation is a good starting point for investigating general trends associated with hot spot ignition and burn [18], care should be taken with regard to its pressure validity regime, as suggested (for pressures of 0.1-5GPa) by Shaw et al [19].…”

Section: Reaction Rates For Nitromethanementioning

confidence: 99%

The evolution of the temperature field during cavity collapse in liquid nitromethane. Part II: reactive case

Michael

Nikiforakis

2018

Shock Waves

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This work is concerned with the effect of cavity collapse in non-ideal explosives as a means of controlling their sensitivity. The main objective is to understand the origin of localised temperature peaks (hot spots) which play a leading order role at the early stages of ignition. To this end, we perform two-and three-dimensional numerical simulations of shock-induced single gas-cavity collapse in liquid nitromethane. Ignition is the result of a complex interplay between fluid dynamics and exothermic chemical reaction.In the first part of this work, we focused on the hydrodynamic effects in the collapse process by switching off the reaction terms in the mathematical formulation. In this part, we reinstate the reactive terms and study the collapse of the cavity in the presence of chemical reactions. By using a multi-phase formulation which overcomes current challenges of cavity collapse modelling in reactive media, we account for the large density difference across the material interface without generating spurious temperature peaks, thus allowing the use of a temperature-based reaction rate law. The mathematical and physical models are validated against experimental and analytic data. In Part I, we demonstrated that, compared to experiments, the generated hot spots have a more complex topological structure and that additional hot spots arise in regions away from the cavity centreline. Here, we extend this by identifying which of the previously determined hightemperature regions in fact lead to ignition and comment on the reactive strength and reaction growth rate in the distinct hot spots. We demonstrate and quantify the sensitisation of nitromethane by the collapse of the isolated cavity by comparing the ignition times of nitromethane due to cavity collapse and the ignition time of the neat material. The ignition in both the centreline hot spots and the hot spots generated by Mach stems occurs in less than half the ignition time of the neat material. We compare two-and three-dimensional simulations to examine the change in topology, temperatures, and reactive strength of the hot spots by the third dimension. It is apparent that belated ignition times can be avoided by the use of three-dimensional simulations. The effect of the chemical reactions on the topology and strength of the hot spots in the timescales considered is also studied, in a comparison between inert and reactive simulations where maximum temperature fields and their growth rates are examined.

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“…It seemed worthwhile to extract Arrhenius parameters from the PETN wedge data in the usual way, 2s3s4 u~lng T2 ti-v '1~exp(TA/To) 1 TFTA whara v !s tha fraquancy factor, Tp is tha ttmparature rioe through the reaction zona, To 1s #hock tempera~ure, qnd TA Induction time tl waa extracted from tha wedge () 1 u-u '1 -t* , -r is activation temperature. data as where t* is time to detonation at the shock front, D is detonation velocity at the pracompraosad density, and U and u are sh~:k and particle v~locitiem r9apectlvely.…”

Section: A3stractmentioning

confidence: 99%

Pop Plot and Arrhenius Parameters for <110> Pentaerythritol Tetranitrate Single Crystals

Dick

1986

Shock Waves in Condensed Matter

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An investigation of the shock initiation of liquid nitromethane

Cited by 66 publications

References 23 publications

Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

The evolution of the temperature field during cavity collapse in liquid nitromethane. Part II: reactive case

Pop Plot and Arrhenius Parameters for <110> Pentaerythritol Tetranitrate Single Crystals

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