Underwater vapor phase burning of aluminum particles and on aluminum ignition during steam explosions
- Fauske and Associates, Inc., Burr Ridge, IL (United States)
Recently reported experimental studies on aluminum-water steam explosions indicate that there may be a critical metal temperature at which the process changes over from a physical explosion to one which is very violent and involves the rapid liberation of chemical energy. In this report we examine the hypothesis that vapor-phase burning of aluminum is a necessary condition for the occurrence of such ignition-type'' steam explosions. An available two-phase stagnation flow film-boiling model is used to calculate the steam flux to the vaporizing aluminum surface. Combining this calculation with the notion that there is an upper limit to the magnitude of the metal vaporization rate at which the reaction regime must change from vapor phase to surface burning, leads to prediction of the critical metal surface temperature below which vapor phase burning is impossible. The critical temperature is predicted for both the aluminum-water pre-mixture configuration in which coarse drops of aluminum are falling freely through water and for the finely-fragmented aluminum drops in the wake of the pressure shock that triggers'' the explosion. Vapor phase burning is predicted to be possible during the pre-mixture phase but not very likely during the trigger phase of a steam explosion. The implications of these findings in terms of the validity of the hypothesis that ignition may begin with the vapor phase burning of aluminum is discussed. Recently postulated, alternative mechanisms of underwater aluminum ignition are also discussed.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (United States); Fauske and Associates, Inc., Burr Ridge, IL (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 5509073
- Report Number(s):
- WSRC-RP-91-1001; CONF-9111204-1; ON: DE92011196
- Resource Relation:
- Conference: Department of Energy AERO meeting, San Francisco, CA (United States), 13 Nov 1991
- Country of Publication:
- United States
- Language:
- English
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