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1.
A historical overview of experimental solid combustion research in microgravity
Wilson Ulises Rojas Alva, Grunde Jomaas, 2022, izvirni znanstveni članek

Povzetek: Studying solid combustion phenomena in microgravity environments can be complex, and this is furthered by many limitations and constraints in the available microgravity research platforms. Consequently, fire safety in spacecraft is also a complex subject. The main limitations found in the field are related to the microgravity quality, the duration of microgravity conditions, the rig capabilities in volume and size, time scales, length scales and the diagnostic systems, and these are therefore the focus in the current investigation. The laboratory capacity of ground-based platforms has remained somewhat stalled since 1990s, some drop towers have recently been upgraded to extend their performance. New space-based platforms have been or are being established and could extend the windows-of-opportunity to perform research. In addition, a discussion is provided on the implications of the fact that the phenomena studied in the experimental investigations and the type of material employed covers both programmatic and scientific needs. It is found that a handful of materials are most widely studied to quantify and characterise some of the phenomena, while some materials have been employed even in single experimental efforts. The current literature review provides a very comprehensive overview of previous experimental studies and the experimental methodologies utilised. Thus, this study can become an aid to planning for future studies.
Ključne besede: Microgravity, research platforms, solid combustion, fire safety, spacecraft
Objavljeno v DiRROS: 13.11.2023; Ogledov: 246; Prenosov: 76
.pdf Celotno besedilo (965,67 KB)
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2.
Flame spread behaviour of Polydimethylsiloxane (PDMS) membranes in 1 g and µg environments
Wilson Ulises Rojas Alva, Frederik Møller-Poulsen, Sze Lok Man, Cameron Creamer, David Hanna, Grunde Jomaas, 2022, izvirni znanstveni članek

Povzetek: Diffusion flame behaviour and silica ash (SiO2) production were experimentally studied for various Polydimethylsiloxane (PDMS) membrane thicknesses (0.125 mm to 1.0 mm) in normal gravity and during microgravity flight experiments. The flames were established on vertical samples (300 mm in length) and subjected to either opposed or concurrent forced flows (both laminar and turbulent), assimilating the NASA Test 1 that is in use for spacecraft material selection. The opposed flame spread rate was observed to be steady and could be estimated using classical theory. Under concurrent flow, the flame spread rate was only steady for very high forced flows. The opposed flame-spread rate ranged from 0.5 to 1.5 mm/s, while the concurrent case ranged between 0.1 and 12 mm/s. The transport of silica ash (SiO2) was found to affect the heat balance of the concurrent flame spread in a manner that resulted in unsteady flame spread. For opposed flame spread, on the other hand, the transport of silica ash showed to be irrelevant. The extinction behaviour for the concurrent flame spread was heavily dominated by the transport of silica-ash, while for opposed flames, extinction was due to kinetics (at high forced flows). In microgravity environments, the transport and deposition of silica ash is anticipated to dominate flame spread and near-limit as well. These results suggest that silica-based products might be less flammable in microgravity than other similar materials such as common thermoplastics (PP or PE) used as wire jackets.
Ključne besede: silicone burning, spacecraft fire safety, flame spread, near-limit, silica-ash
Objavljeno v DiRROS: 13.11.2023; Ogledov: 312; Prenosov: 80
.pdf Celotno besedilo (1,61 MB)
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