Validation of the Gurney Model in Planar Geometry for a Conventional Explosive

Loiseau, Jason; Georges, William; Higgins, Andrew

doi:10.1002/prep.201500246

Cited by 13 publications

(6 citation statements)

References 30 publications

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“…An array of twisted wire pairs mounted at the top of the charge were used to measure detonation velocity. Based on the work by Souers [8] and a prior paper by the authors [9], tilt-correction based on the Taylor model was used to extract terminal material velocity to determine AA.…”

Section: Methodsmentioning

confidence: 99%

Scaling of the propulsive capability of aluminized gelled nitromethane

Loiseau

Georges

Frost

et al. 2018

AIP Conference Proceedings

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Small mass fractions (< 20%) of micron-scale aluminium particles added to a high explosive can react quickly and with sufficient exothermicity to improve metal-acceleration ability (AA) relative to an equal volume of only the base explosive. In order for the aluminium to increase AA, exothermicity must more than offset losses in gas-production and from heating and accelerating the solid particles in the flow. Furthermore, particles must react promptly to deliver this energy prior to loss in driving pressure from product expansion or acoustic decoupling from the driven material. For these reasons, many aluminized formulations exhibit slight or no increase in AA. Furthermore, AA is typically studied using the cylinder test, which specifies a fixed, heavy copper wall. In the present study the authors have used symmetric sandwiches of flyer plates of widely different thicknesses to examine how charge scaling and plate acceleration time-scales influence the enhancement in AA for different sizes of aluminium particles. Nitromethane gelled with 4% Poly(methyl methacrylate) by mass was used for the explosive. 3M K1 microballoons were added at a mass fraction of 0.5% to sensitize the mixture. Aluminium with a mean particle size of 3.5 µm or 108 µm was added at 15% total mixture mass fraction. At 15% mass fraction, an enhancement in AA was observed for both particle sizes and flyer configurations. Results indicated an onset of reaction close to the sonic plane of the detonation wave.

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Section: Methodsmentioning

confidence: 99%

Scaling of the propulsive capability of aluminized gelled nitromethane

Loiseau

Georges

Frost

et al. 2018

AIP Conference Proceedings

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“…The two configurations are depicted schematically in Figure 1. Further details on the experimental setups are provided in references [7] and [13]. Flyer thickness was varied from 0.25 mm to 25.4 mm in both charge geometries to obtain the desired range of M/C.…”

Section: Methodsmentioning

confidence: 99%

“…Non-coincident measurements simplified correction for flyer tilt and forward flyer motion to obtain the total metal velocity. Correction used the Taylor tubular bomb model applied to PDV following prior analysis by Souers [14] and the authors [7].…”

Section: Methodsmentioning

confidence: 99%

“…Nitromethane (NM) is an attractive explosive for studying non-ideal effects since it is a miscible liquid and it can be readily thickened with a variety of additives to create particle suspensions. The authors also previously demonstrated that neat, amine-sensitized NM follows Gurney scaling [7]. Gelling of neat NM permitted the dispersion and suspension of glass microballoons (GMBs): a low-density, solid diluent.…”

Section: Introductionmentioning

confidence: 95%

“…The Gurney model is thus primarily a scaling law that describes the efficiency of energy transfer as the relative charge masses are varied. Its engineering utility has been repeatedly demonstrated experimentally by various authors [5,6,7].…”

Section: Introductionmentioning

confidence: 99%

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Non-Gurney scaling of explosives heavily loaded with dense inert additives

Loiseau

Georges

Frost

et al. 2018

AIP Conference Proceedings

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For most high explosives, the ability to accelerate material to some terminal velocity scales with the ratio of materialmass to charge-mass (M/C) according to the Gurney model. In planar geometry, the Gurney model accurately estimates the terminal velocity of the driven material until M/C is reduced to 0.2 or lower. Below this value, gasdynamic departures from the assumptions of the model result in under-prediction of the material terminal velocity. In the present study, a modified Gurney model was used to predict the scaling of flyer velocity with M/C for explosives heavily diluted with either low density (3M K1 glass microballoons-GMBs), or high density (steel beads) diluent. The modified model accounted for explosive energy being transferred to accelerate the diluent. The model was compared with a series of flyer experiments propelled using either Poly(methyl methacrylate)-gelled nitromethane (96% NM/4% PMMA) diluted with 10% GMBs by mass or diethylenetriamine-sensitized liquid nitromethane saturating a packed bed of steel particles. Both grazing and normally incident detonations of the test mixtures were used to propel the flyers. The Gurney model accurately predicted the terminal velocity for the gelled NM/GMB mixture although it did not account for the contribution from the detonation shock nor the initiating slapper plate. The model failed to predict flyer velocity for the NM/steel mixture. The propulsive efficiency of this mixture increased with M/C relative to the baseline explosive so that the model under-predicted velocity for small M/C but over-predicted for large M/C.

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