Calculation of the shock waves from spherical explosive charges in air

Fonarev, A. S.; Chernyavskii, S. Yu.

doi:10.1007/bf01029553

“…The contact front does not stop when the ambient counteraction force levels off the driving piston force. There is an overexpansion effect similar to that found in numerical simulations of a spherical gas source [27] and explosive expansion into air of varying pressure [28]. This means that the pressure in the region of vaporized products goes down below pressure level of the undisturbed ambient gas.…”

Section: D Model and Numerical Resultssupporting

confidence: 54%

Gas-dynamic effects of the interaction between a pulsed laser-ablation plume and the ambient gas: analogy with an underexpanded jet

Bulgakov

¹

,

Bulgakova

²

1998

J. Phys. D: Appl. Phys.

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The expansion of a laser-ablation plume into different ambient gases is investigated theoretically using a two-fluid gas-dynamic model and experimentally with time-of-flight mass spectrometry. Both calculations and measurements, performed for laser ablation of Cu in oxygen or noble gases, reveal an oscillatory behaviour of plume expansion dynamics which is strongly dependent on the molecular weight of the ambient gas. Simple gas-dynamic considerations based on the analogy between an ablation plume and a supersonic underexpanded gaseous jet are found to explain a number of the effects of the interaction between the plume and the background gas. The effect of plume focusing observed previously at fairly high pressures of various ambient gases is reasonably described using the phenomenology of the underexpanded jet. The analogy also predicts vortex formation at the plume periphery.

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“…

In the point explosion problem it is assumed that an instantaneous release of finite energy causing shock wave propagation in the ambient gas occurs at a space point.The results of the solution of the problem of such blasts are contained in [1][2][3][4].This point model is applied for the determination of shock wave parameters when the initial pressure in a sphere of finite radius exceeds the ambient air pressure by 2-3 orders of magnitude.The possibility of such a flow simulation at a certain distance from the charge is shown in papers [4,5] as applied to the blast of a charge of condensed explosive and in [6,8] as applied to the expansion of a finite volume of strongly compressed hot gas.In certain practical problems the initial pressure in a volume of finite dimensions exceeds atmospheric pressure by a factor 10-15 only. Such cases arise, for example, in the detonation of gaseous fuel---air mixtures.

…”

mentioning

confidence: 99%

“…The possibility of such a flow simulation at a certain distance from the charge is shown in papers [4,5] as applied to the blast of a charge of condensed explosive and in [6,8] as applied to the expansion of a finite volume of strongly compressed hot gas.…”

mentioning

confidence: 99%

Blast wave propagation in air from a gaseous charge

Ashratov¹,

Pirumov²,

Сурков³

1986

Fluid Dyn

0

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In the point explosion problem it is assumed that an instantaneous release of finite energy causing shock wave propagation in the ambient gas occurs at a space point.The results of the solution of the problem of such blasts are contained in [1][2][3][4].This point model is applied for the determination of shock wave parameters when the initial pressure in a sphere of finite radius exceeds the ambient air pressure by 2-3 orders of magnitude.The possibility of such a flow simulation at a certain distance from the charge is shown in papers [4,5] as applied to the blast of a charge of condensed explosive and in [6,8] as applied to the expansion of a finite volume of strongly compressed hot gas.In certain practical problems the initial pressure in a volume of finite dimensions exceeds atmospheric pressure by a factor 10-15 only. Such cases arise, for example, in the detonation of gaseous fuel---air mixtures. The present paper considers the problem of shock wave propagation in air, caused by explosion of gaseous charge of spherical or cylindrical shape.A numerical solution is obtained in a range of values of the specific energy of the charge characteristic for fuel--air detonation mixtures by means of the method of characteristics without secondary shock wave separation.The influence of the initial conditions of the gas charge explosion (specific energy, nature of initiation, and others) is investigated and compared with the point case with respect to the pressure difference across the shock wave and the positive overoressure pulse.

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