Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session Q5: EM.1 Detonation I |
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Chair: Tariq Aslam, Los Alamos National Laboratory Room: Cascade I |
Wednesday, July 10, 2013 1:45PM - 2:00PM |
Q5.00001: The influence of small additions of diethylenetriamine on the detonation waves stability for nitromethane/acetone solution Valentina Mochalova, Alexander Utkin Instability of detonation front in nitromethane/acetone (NM/A) solution was observed in our previous work: at 10{\%} of acetone the amplitude of heterogeneities was about 20 microns and at 20{\%} of acetone this size was 50 microns. It is known that small additions of diethylenetriamine (DETA) considerably increase the initial rate of chemical reaction in detonation wave for NM. It was expected that DETA influences on the stability of detonation waves in NM/A solution too. To investigate this phenomenon laser interferometer VISAR was used for recording of particle velocity profiles in detonation waves for NM/A. It was found that at addition of 0,5{\%} DETA to NM/A 90/10 the oscillations in velocity profile decrease in several times. And at 1{\%} DETA the profile is smooth, i.e. the heterogeneities disappear and detonation wave becomes steady-state. In NM/A 80/20 at addition of 5{\%} DETA the heterogeneities size is reduced by the order. The increase of detonation wave velocity of NM/A more than 1{\%} was observed at small concentrations of DETA. Thus it was found that small additions of DETA to NM/A solution with unstable detonation front result not only in decrease heterogeneities size but in their disappearance and stabilization of detonation waves. [Preview Abstract] |
Wednesday, July 10, 2013 2:00PM - 2:15PM |
Q5.00002: Detonation Reaction Zone Measurements of PBX 9501 and PBX 9502 Samuel Vincent, Mark Short, Scott Jackson Explosives are often confined by inert materials. During detonation, the high pressures associated with the detonation reaction zone and expansion of products induce motion in the confiner. Classical programmed burn models for conventional high explosives (CHEs) performance do not aim to accurately capture the contribution to CHE drive from the short (100-200 micron) detonation reaction zone, as the drive is dominated by expansion of detonation products. However, the reaction zone lengths of insensitive (millimeter-scale) and non-ideal explosives (millimeter-to-centimeter-scale) are long enough that a significant contribution to the HE work on the confiner occurs within the reaction zone. Thus accurate prediction of the reaction zone flow structure and mechanical state is crucial to accurately model the motion of confiners driven by insensitive and non-ideal explosives. In this work, we have measured particle velocity profiles of detonation reaction zones in PBX 9501 and PBX 9502 slab geometries at the breakout surface using PDV imaging through LiF windows. We compare this data to model predictions in the slab geometry using the Wescott-Stewart-Davis reactive burn model and comment on the model performance. [Preview Abstract] |
Wednesday, July 10, 2013 2:15PM - 2:30PM |
Q5.00003: CREST Modelling of PBX 9502 Corner Turning Experiments at Different Initial Temperatures Nicholas Whitworth Corner turning is an important problem in regard to detonation wave propagation in TATB-based explosives. Experimentally, a sudden change in direction of the propagating wave, such as turning a sharp corner, can result in dead-zones being left behind in the corner turn region, with the observed behaviour being particularly sensitive to the initial temperature of the explosive. In this paper, the entropy-dependent CREST reactive burn model is used to simulate corner turning experiments on the TATB-based explosive PBX 9502. Calculated results of double cylinder tests at three different initial temperatures (-54$^\circ$C, 25$^\circ$C, and 75$^\circ$C), and a ``hockey puck" experiment at ambient temperature, are compared to the corresponding test measurements. The results show that the model is able to: (i) calculate persistent dead-zones in PBX 9502 without recourse to any shock desensitisation treatment, and (ii) predict changes in corner turning behaviour with initial temperature using one set of coefficients. [Preview Abstract] |
Wednesday, July 10, 2013 2:30PM - 2:45PM |
Q5.00004: Understanding Detonation Corner Turning within Ultra-Fine TATB: Measurements and Modeling Jose Sinibaldi, Peter Vitello, Chadd May Detonation corner turning within insensitive high explosives has demonstrated difficulties as the insensitivity of the high explosive increases. Experiments tend to report {\it breakout profiles}, which show times of arrival of the detonation wave at the surface of the IHE charge. Although, various reactive flow models are able to predict these {\it breakout profiles}, none of these models agree perfectly with each other. Models predict major differences in pressure profiles and in the internal detonation wave propagation characteristics. Thus, the objective of this study was to provide detailed accounts of the wave propagation within an ultra-fine TATB charge, through the use embedded fiber-optic diagnostics that allowed measuring the detonation wave propagation within the ultra-fine TATB charges. In addition, these experiments were also instrumented at multiple points with Photonic Doppler Velocimetry to provide dynamic pressure profiles at the hemispherical surface; and orthogonal streak cameras to provide the conventional {\it breakout profiles}. Comparisons between experimental data and simulation results using a high resolution reactive flow model for ultra-fine TATB will be presented. [Preview Abstract] |
Wednesday, July 10, 2013 2:45PM - 3:15PM |
Q5.00005: On the verification and validation of detonation models Invited Speaker: James Quirk This talk will consider the verification and validation of detonation models, such as Wescott-Stewart-Davis (Journal of Applied Physics. 2005), from the perspective of the American Institute of Aeronautics and Astronautics policy on numerical accuracy (AIAA J. Vol. 36. No. 1, 1998). A key aspect of the policy is that accepted documentation procedures must be used for journal articles with the aim of allowing the reported work to be reproduced by the interested reader. With the rise of electronic documents, since the policy was formulated, it is now possible to satisfy this mandate in its strictest sense: that is, it is now possible to run a comptuational verification study directly in a PDF, thereby allowing a technical author to report numerical subtleties that traditionally have been ignored. The motivation for this document-centric approach is discussed elsewhere (Quirk2003, Adaptive Mesh Refinement Theory and Practice, Springer), leaving the talk to concentrate on specific detonation examples that should be of broad interest to the shock-compression community. [Preview Abstract] |
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