Isolated Single Droplet Combustion: FLEX Experiments onboard the International Space Station
Vedha Nayagam, Daniel L. Dietrich, Forman A. Williams
Test conditions.
Extracted from the paper by AI · “Verified” means a person checked it
| Fuel | O₂ | Pressure | Airflow | Sensors | Source | AI conf. | Status |
|---|---|---|---|---|---|---|---|
| Methanol Droplet |
13% < O2 < 30% | Atmospheric pressure (implied by LOI context) | Microgravity (ISS) | Backlit, black and white high speed camera, LLUV flame view camera, Color camera, Radiometers | p. 4 | 95% | Pending |
| n-decane Droplet |
21% O2 and 79% N2 | 0.5 atm | Microgravity (ISS) | Backlit, black and white high speed camera, LLUV flame view camera, Radiometers | p. 6 | 95% | Pending |
| n-dodecane Droplet |
Air (~21% O2) | 1 atm | Microgravity (ISS) | Backlit, black and white high speed camera, LLUV flame view camera, Radiometers | p. 13 | 90% | Pending |
| n-dodecane Droplet |
Air (~21% O2) | 3 atm | Microgravity (ISS) | Backlit, black and white high speed camera, LLUV flame view camera, Radiometers | p. 13 | 90% | Pending |
Findings.
-
01
The limiting oxygen index (LOI) for methanol droplet combustion is approximately 12-13% oxygen at atmospheric pressure.
Prevention · p. 4 · AI confidence 95% · Reported · Pending
“The limiting oxygen index (LOI) ~ 12 -13% oxygen at atmospheric pressure.”
-
02
Cool flames are fundamentally different from hot flames as they are controlled by chemical kinetics in the Negative Temperature Coefficient (NTC) region.
Other · p. 8 · AI confidence 90% · Reported · Pending
“Cool flames are fundamentally different compared to hot -flames (chemical kinetics controlled)!”
-
03
Cool flames are weak, broad, and located closer to the droplet surface compared to hot flames.
Detection · p. 7 · AI confidence 90% · Reported · Pending
“Cool flames are very weak ... They are broad ... They are located closer to the droplet surface compared to the hot flames”
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04
Cool flames produce partially oxidized fuel that can potentially re-ignite to hot flames, posing fire safety concerns in spacecraft.
Prevention · p. 14 · AI confidence 95% · Reported · Pending
“These cool flames produce partially oxidized fuel and potentially re -ignite to hot flames posing fire safety concerns in spacecraft environments”
-
05
Existing detailed chemical kinetic models do not accurately predict second-stage cool flame extinction and warm flame behavior.
Other · p. 14 · AI confidence 90% · Reported · Pending
“Existing, widely -used detailed chemical kinetic models do not accurately predict the 2 ndstage cool flame extinction (and warm flame) and need further improvement”
-
06
At elevated pressures (3 atm), n-dodecane exhibits warm flames and oscillatory extinction.
Other · p. 13 · AI confidence 90% · Reported · Pending
“Warm flames ... Oscillatory extinction observed for the first time”