An experimental study of deflagration to detonation transition supported by dust layers
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering
The roles which dust layers play in severe dust explosions were investigated in a 70-m-long and 30-cm-diameter horizontal Flame Acceleration Tube (FAT) with one end closed and the other end open to the atmosphere. A variety of dusts such as corn dust, cornstarch, Mira Gel starch, wheat dust, and wood flour were layered on the bottom half of the FAT. Flame and detonation propagation parameters were closely monitored at different locations along the FAT. The study demonstrated that the moisture content of the dust, the exposed area of the dust layers to the convective flow, and the physical characteristics of the dust are the factors that most determine the severity of layered dust explosions, indicating that prelayered dust combustion is dominated by the dust/air mixing process. While the dust explosion rate constant K{sub st} can be used to characterize dust explosibility in predispersed dust in constant volume enclosures, it does not appear to characterize the behavior of layered dust explosions. Qualitative measurements of the variation of dust concentration during a layered dust explosion were obtained. The measurements indicated that the dust concentration at the time of flame arrival is highly nonuniform. The maximum pressure rise (P{sub max} {minus} P{sub 0}) within the FAT during a layered dust explosion was found to vary linearly with the flame velocity V{sub f} when V{sub f} is subsonic. As V{sub f} reaches supersonic values the maximum pressure increase was found to vary with the V{sub f}{sup 2}, the square of the flame velocity. This result was found to be independent of dust type and concentration.
- OSTI ID:
- 28068
- Report Number(s):
- CONF-940711-; ISSN 0010-2180; TRN: IM9516%%194
- Journal Information:
- Combustion and Flame, Vol. 100, Issue 3; Conference: 25. international symposium on combustion, Irvine, CA (United States), 31 Jul - 5 Aug 1994; Other Information: PBD: Feb 1995
- Country of Publication:
- United States
- Language:
- English
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