Photographic Evidence for the Mechanism of Fragmentation of a Single Drop of Melt in Triggered Steam Explosion Experiments

Nelson, Lloyd S.; Duda, P.M.

doi:10.1515/jnet.1988.13.1.27

Cited by 23 publications

(1 citation statement)

References 7 publications

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“…The parameters of the experimental series A, B, and C were adjusted so that each fragmentation process acted on the melt in comparable proportion and intensity in all three series (seven runs each). Additional fragmentation was expected to occur with increasing kinetic energy release from B and A relative to C. Furthermore, a specific fragmentation mechanism was predicted and described during the fine-fragmentation phase of MFCI [Nelson et al, 1988;FrShlich, 1991;Zimanowski et al, 1991Zimanowski et al, , 1995a. These studies, however, were based on indirect observations only, and a direct proof of the existence and abundance of these particles (i.e., interactive particles) has not yet been achieved.…”

Section: Discussionmentioning

confidence: 99%

Fragmentation of basaltic melt in the course of explosive volcanism

Zimanowski¹,

Büttner²,

Lorenz³

et al. 1997

J. Geophys. Res.

197

131

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Abstract. With the aim to enhance interpretation of fragmentation mechanisms during explosive volcanism from size and shape characteristics of pyrodasts experimental studies have been conducted using remelted volcanic rock (olivine-melilitite). The melt was fragmented and ejected from a crucible by the controlled release of pressurized air volumes (method 1) or by controlled generation of phreatomagmatic explosions (Molten Fuel Coolant Interaction (MFCI); method 2). Both methods were adjusted so that the ejection history of the melt was identical in both cases. The experiments demonstrate that exclusively during MFCI, angular particles in the grain size interval 32 to 130 ptm are generated that show surface textures dominated by cracks and pitting. The physical process of their generation is described as a brittle process acting at cooling rates of > 106 K/s, at stress rates well above 3 GPa/m 2, and during ~700 pts. In this time period the emission of intense shock waves in the megahertz range was detected, releasing kinetic energy of > 1000 J. By both experimental methods, three more types of particles were produced in addition, which could be identified and related to the acceleration and ejection history of the melt: spherical particles, elongated particles, and Pele's hair. Abundance and grain size distribution of these particles were found to be proportional to the rate of acceleration and the speed of ejection but were not influenced by the experimental method used. Pele's hair occurred at ejection speeds of >75 m/s.

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Section: Discussionmentioning

confidence: 99%

Fragmentation of basaltic melt in the course of explosive volcanism

Zimanowski¹,

Büttner²,

Lorenz³

et al. 1997

J. Geophys. Res.

197

131

View full text Add to dashboard Cite

show abstract

Vapor film collapse around hot liquid drops when an external pressure wave is supplied

Takashima

Iida

2000

Heat Trans. Asian Res.

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Vapour explosions: multiphase detonations or deflagrations?

Fletcher

1994

Shock Waves

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This paper contains a discussion of the various modes of propagation which may occur when a hot melt transfers its energy explosively to a cold volatile liquid. In particular, the possibility of the existence of detonation-like and deflagration-like behaviour is discussed and two different melt droplet fragmentation models which may lead to these two types of behaviour are presented. The transient, multiphase flow code CULDESAC is used to perform calculations for the two different cases and the theoretical existence of the two modes of propagation is established. Using results from the calculations it is concluded that the shape of the predicted pressure pulse observed in experiments is closer to the detonation-like solution obtained here. However, it is noted that careful experimental comparison is needed before any firm conclusions can be drawn.

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Photographic Evidence for the Mechanism of Fragmentation of a Single Drop of Melt in Triggered Steam Explosion Experiments

Cited by 23 publications

References 7 publications

Fragmentation of basaltic melt in the course of explosive volcanism

Fragmentation of basaltic melt in the course of explosive volcanism

Vapor film collapse around hot liquid drops when an external pressure wave is supplied

Vapour explosions: multiphase detonations or deflagrations?

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