Gravity Induced Separation in “Liquid Flames”

Shkadinsky, K. G.; Shkadinskaya, G. V.; Matkowsky, B. J.

doi:10.1080/00102209608935531

Cited by 12 publications

(8 citation statements)

References 4 publications

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“…Nor do we consider the condensed medium as a multicomponent mixture with relative motion between the components, as in Shkadinsky et al (1996), Shkadinsky et al (1998). Finally, we employ a simplified single stage kinetic law.…”

Section: Resultsmentioning

confidence: 99%

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Gas-Phase Influence on Quasisteady “Liquid Flames” in Gravitational Fields

Shkadinsky

Shkadinskaya

Matkowsky

2000

Combustion Science and Technology

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We consider the SHS (self-propagating high-temperature synthesis) process for synthesizing materials. In this process a powder mixture of reactants is cold pressed into a sample, which is ignited at one end. A high temperature combustion wave then propagates through the sample converting reactants to the desired product materiaL In this process. melting of some or all the components is often observed. Therefore, we study combustion waves propagating through a high caloricity inorganic powder mixture whose combustion temperature exceeds the melting temperatures of many components. The solid matrix is thus destroyed by the propagating combustion wave due to melting ahead of the reaction lone, and a liquid bath is formed which contains gaseous bubbles. The waves propagate in the presence of a gravitational field. Due to the effect of gravity, there is relative motion between the rising bubbles and the descending bath, which affects the composition of the medium, its therrnophysical properties, the "liquid flame" structure, and the propagation velocity. To enhance our understanding of phenomena associated with the interaction ofthe relative motion with the propagating combustion wave we formulate and analyze a relatively simple mathematical model of liquid flames in a gravitational field, We describe the wave structure and combustion characteristics including the combustion velocity. We compare our results to existing experimental observations and suggest new experiments to be performed. We consider the effects of gravity and, in particular, examine both microgravity and large gravity conditions.

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Section: Resultsmentioning

confidence: 99%

“…That is, we consider one effect at a time by isolating that effect. Thus, in previous studies (Shkadinsky et al (1996), Shkadinsky et al (1998). Raymond et al (1998». we considered the combustion problem in a liquid bath containing condensed particles.…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Influence on Quasisteady “Liquid Flames” in Gravitational Fields

Shkadinsky

Shkadinskaya

Matkowsky

2000

Combustion Science and Technology

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“…With few exceptions [3], these reactions reach sufficiently high temperatures that result in the melting of one or more of the reactants or the products [1]. The existence of a liquid phase can lead to phase segregation when differences of density between solid and liquid phases are significant and the capillary coalescence of liquid droplets is favorable [4]. These conditions have been utilized in SHS reactions to separate product phases under higher gravitational conditions [5].…”

Section: Introductionmentioning

confidence: 99%

Dissolution and precipitation under gravitational conditions in the W–Al system

Unuvar¹,

Fredrick²,

Anselmi‐Tamburini³

et al. 2007

Intermetallics

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“…In contrast, microgravity conditions are appropriate if relative motion of the components is undesirable and is to be suppressed (Shteinberg et al (1991), Goroshin, Lee, Frost (1994». Another example of a liquid bath containing particles ahead of an exothermic reaction zone, with gravity significantly affecting the wave propagation, occurs in frontal polymerization (Pojman et at. (1992». There have been only a few theoretical studies of "liquid flames" (e.g., Shkadinsky et at. (1996).…”

Section: Introductionmentioning

confidence: 98%

Slowly and Rapidly Propagating “Liquid Flames” in Gravitational Fields

Shkadinsky¹,

Shkadinskaya²,

Matkowsky³

2000

Combustion Science and Technology

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We consider the combustion, in a gravitational field, of a heterogeneous powder mixture compressed into a solid sample, in which the high temperature ahead of the reaction zone destroys the solid, due, e.g. to melting of some of components of the mixture. Thus, a suspension is formed, consisting of a liquid bath containing solid or liquid particles. Processes such as heat and mass transfer as well as chemical reactions in the suspension determine the structure of the combustion wave and its propagation velocity. Under the influence of gravitational forces there is the possibility of relative motion of the liquid and solid. Previous theoretical analyses considered the rate of heat transfer between the solid and liquid phases to be sufficiently large that their two distinct temperatures rapidly equilibrated to a single temperature. In addition to this case, we also consider the case when the rate of heat transfer is not so large and the model involves the separate temperatures of the solid and liquid phases. We find that multiplicity of traveling wave structures is possible. In particular, in addition to a low velocity structure, which is essentially the same as that obtained from the one temperature description, we find a high velocity structure, which does not exist in the one temperature description, but rather depends on the fact that the solid and fluid temperatures differ from each other. Both structures can exist for the same parameter values in a given range. We describe the dependence of the combustion characteristics of the two structures on gravitational forces and other factors. In particular. we compare the characteristics in gravity and microgravity environments.

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Gravity Induced Separation in “Liquid Flames”

Cited by 12 publications

References 4 publications

Gas-Phase Influence on Quasisteady “Liquid Flames” in Gravitational Fields

Gas-Phase Influence on Quasisteady “Liquid Flames” in Gravitational Fields

Dissolution and precipitation under gravitational conditions in the W–Al system

Slowly and Rapidly Propagating “Liquid Flames” in Gravitational Fields

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