Skip to content

Ask the SI:

Experiments / ACME burners

CFI-GSupports fire safety

Cool Flames Investigation with Gases

Found the conditions under which gas-fed spherical flames turn into cool flames, including the highest-oxygen tests in PSI.

NASA's own record
A spherical flame around a small porous burner.
A spherical flame on the CFI-G burner. NASA photograph, from PSI.

What burned

Gas

N-butane, propane and ethane

Where

On the space station

In orbit, where everything is weightless

How much data

333 tests

Each one is a row in NASA's table

What they changed between tests

  • fuel
  • oxygen concentration
  • pressure
  • fuel dilution
  • flow rate
  • flame direction

What it found

  1. 1 of 2

    Its high oxygen values belong to "inside-out" flames, where oxygen is injected into fuel - not to an oxygen-rich cabin atmosphere.

    NASA's words

    “an oxygen-nitrogen mixture of up to 85% oxygen flowed from the spherical burner creating an inside-out flame” NASA challenge statement

  2. 2 of 2

    The tests span reduced and elevated pressures for both flame directions.

    NASA's words

    “Consider multiple fuels, a range of reactant dilutions, flow rates, and pressures for normal and inverse convection directions.” PSI record

Summarized by the SI. Each summary is tied to a quotation that the build checks against NASA's text. A matching quote is not a scientific review.

What it helps with

  • Stopping a fire from starting

    Which materials burn, and in what air

    A clear part

  • Noticing a fire early

    What smoke looks like to a detector

    Not an aim

  • Putting a fire out

    What makes a flame go out

    Touches on it

For researchers: NASA's full recordThe conditions tested, every row of the table, NASA's description, publications and hardware
ISSMicrogravity InvestigationACME burnersCompare with othersdoi:10.60555/cyt1-kh64

Shared hardware: Six gas-flame experiments shared one modular set of burners and diagnostics. Experiments that shared hardware share its limits, so their results can be compared directly.

Why it counts as fire-safety research

“Microgravity tests with the highest oxygen concentrations were conducted as part of the ACME's Cool Flames Investigation with Gases (CFI-G).” NASA challenge statement

NASA's words behind each rating

  • Prevention2 of 3

    “Determine the conditions for which cool diffusion flames occur for propane, n-butane, and n-pentane”

  • Detection0 of 3

    Not an aim of this investigation.

  • Suppression1 of 3

    “Cool diffusion flames for which a decrease in fluent flow rate will cause extinction”

Conditions covered

Oxygen in the atmosphere
18% to 40%
burner stream up to 85%
Pressure
49.5 kPa to 331 kPa
Flow speed
not reported
not in the PSI table
Itemized rows
333
333 tests

Fuels and materials

n-butane (140), propane (99), ethane (94)

Measurements named in the PSI record

  • Flame imaging
  • Radiometry
  • Thermocouples
  • Chemiluminescence

How the tests differ, and how they are the same

Worked out from the 333 rows of the PSI table. A variable that is not listed was not reported, which is different from being held fixed.

Changed from test to test

Oxygen
12% to 85%
Oxygen refers to
2 different values
Pressure
49.5 kPa to 331 kPa
Fuel or material
3 different values
Fuel fraction
0% to 100%
Fuel flow rate
0 mg/s to 3.21 mg/s
Oxidizer flow rate
0.931 mg/s to 9.08 mg/sreported in 154 of 333 rows
Ignited
3 different values
Burn time
0 s to 304 sreported in 329 of 333 rows
How the test ended
2 different valuesreported in 272 of 333 rows
Cool flame observed
2 different valuesreported in 8 of 333 rows
Flame colour
5 different valuesreported in 120 of 333 rows
Oxygen at end of test
17.9% to 39.7%reported in 179 of 333 rows
Adiabatic flame temperature
1,397 K to 2,978 K
Stoichiometric mixture fraction
0.0588 to 0.784
Peak burner temperature
25.6 °C to 651.5 °Creported in 284 of 333 rows
Photomultiplier tube 1 gain setting
4.5 to 10reported in 328 of 333 rows
Photomultiplier tube 3 gain setting
5 to 10reported in 328 of 333 rows

The same in every test

Fuel phase
gas
Geometry
spherical burner

Rows from the PSI table

Click a row for the source of every value. Filter and export

RecordTypeFuel or materialShapeOxygenPressureFlow, cm/sOutcomeDate
21196 A1Testethanespherical burner21%stream110 kPadid not ignite
21196 A2Testethanespherical burner21%stream110 kPaflow terminated
21196 F1Testethanespherical burner15%stream110 kPaflow terminated
21196 H1Testethanespherical burner12%stream110 kPadid not ignite
21196 J1Testethanespherical burner13.5%stream110 kPaself-extinguished
21196 F2Testethanespherical burner15%stream110 kPaflow terminated
21196 F3Testethanespherical burner15%stream110 kPaself-extinguished
21196 F4Testethanespherical burner15%stream110 kPaself-extinguished
21196 F5Testethanespherical burner15%stream110 kPaself-extinguished
21196 F6Testethanespherical burner15%stream110 kPaflow terminated
21196 K1Testethanespherical burner15%stream49.5 kPaself-extinguished
21196 L1Testethanespherical burner21%stream49.5 kPaself-extinguished
21196 L2Testethanespherical burner21%stream49.5 kPaflow terminated
21196 M1Testethanespherical burner30%stream49.5 kPaself-extinguished
21196 M2Testethanespherical burner30%stream49.5 kPaflow terminated
21196 M2_1Testethanespherical burner30%stream49.5 kPaflow terminated
21202 A1Testethanespherical burner85%stream221 kPadid not ignite
21202 A2Testethanespherical burner85%stream221 kPaself-extinguished
21202 A3Testethanespherical burner85%stream221 kPaself-extinguished
21202 A4Testethanespherical burner85%stream221 kPaself-extinguished
21202 H1Testethanespherical burner85%stream221 kPaself-extinguished
21202 H2Testethanespherical burner85%stream221 kPaself-extinguished
21202 H3Testethanespherical burner85%stream221 kPaflow terminated
21202 H4Testethanespherical burner85%stream221 kPaself-extinguished
21202 J1Testethanespherical burner85%stream221 kPaself-extinguished
21202 K1Testethanespherical burner85%stream110 kPaself-extinguished
21202 K2Testethanespherical burner85%stream110 kPaself-extinguished
21202 L1Testethanespherical burner85%stream110 kPaself-extinguished
21209 A1Testethanespherical burner85%stream55.2 kPaflow terminated
21209 A2Testethanespherical burner85%stream55.2 kPadid not ignite
21209 A3Testethanespherical burner85%stream55.2 kPaflow terminated
21209 B1Testethanespherical burner85%stream55.2 kPaflow terminated
21209 A4Testethanespherical burner85%stream55.2 kPaflow terminated
21209 H1Testethanespherical burner50%stream55.2 kPaflow terminated
21209 J1Testethanespherical burner30%stream55.2 kPaflow terminated
21209 F1Testethanespherical burner21%stream55.2 kPaflow terminated
21209 F2Testethanespherical burner21%stream55.2 kPaflow terminated
21209 F3Testethanespherical burner21%stream55.2 kPaflow terminated
21209 B2Testethanespherical burner85%stream55.2 kPaflow terminated
21209 K1Testethanespherical burner18%stream55.2 kPaflow terminated
21216 A1Testethanespherical burner85%stream331 kPaself-extinguished
21216 A2Testethanespherical burner85%stream331 kPaself-extinguished
21216 A3Testethanespherical burner85%stream331 kPaself-extinguished
21216 A4Testethanespherical burner85%stream331 kPaself-extinguished
21216 A5Testethanespherical burner85%stream331 kPaself-extinguished
21216 A6Testethanespherical burner85%stream331 kPaflow terminated
21216 B1Testethanespherical burner85%stream331 kPaself-extinguished
21216 C1Testethanespherical burner50%stream331 kPaself-extinguished
21216 F1Testethanespherical burner21%stream331 kPaflow terminated
21216 H1Testethanespherical burner85%stream110 kPaself-extinguished
21216 H2Testethanespherical burner85%stream110 kPaself-extinguished
21216 J1Testethanespherical burner50%stream110 kPaself-extinguished
21216 K1Testethanespherical burner21%stream110 kPaflow terminated
21222 A1Testpropanespherical burner85%stream331 kPaself-extinguished
21222 A2Testpropanespherical burner85%stream331 kPaself-extinguished
21222 A3Testpropanespherical burner85%stream331 kPaself-extinguished
21222 A4Testpropanespherical burner85%stream331 kPaself-extinguished
21222 A5Testpropanespherical burner85%stream331 kPaself-extinguished
21222 B1Testpropanespherical burner85%stream331 kPaself-extinguished
21222 C1Testpropanespherical burner50%stream331 kPaself-extinguished
21222 C2Testpropanespherical burner50%stream331 kPaself-extinguished
21222 F1Testpropanespherical burner21%stream331 kPaself-extinguished
21222 F2Testpropanespherical burner21%stream331 kPadid not ignite
21228 A1Testpropanespherical burner85%stream221 kPaself-extinguished
21228 A2Testpropanespherical burner85%stream221 kPaself-extinguished
21228 A3Testpropanespherical burner85%stream221 kPaself-extinguished
21228 A4Testpropanespherical burner85%stream221 kPaself-extinguished
21228 B1Testpropanespherical burner85%stream221 kPaself-extinguished
21228 C1Testpropanespherical burner50%stream221 kPaself-extinguished
21228 C2Testpropanespherical burner50%stream221 kPaflow terminated
21228 C3Testpropanespherical burner50%stream221 kPaself-extinguished
21228 C4Testpropanespherical burner50%stream221 kPaself-extinguished
21228 F1Testpropanespherical burner21%stream221 kPaflow terminated
21228 H1Testpropanespherical burner85%stream110 kPaself-extinguished
21228 H2Testpropanespherical burner85%stream110 kPaself-extinguished
21228 J1Testpropanespherical burner85%stream110 kPaself-extinguished
21228 K1Testpropanespherical burner50%stream110 kPaself-extinguished
21228 K2Testpropanespherical burner50%stream110 kPaself-extinguished
21228 L1Testpropanespherical burner21%stream110 kPaself-extinguished
21228 L2Testpropanespherical burner21%stream110 kPaflow terminated
21235 A1Testpropanespherical burner85%stream110 kPaflow terminated
21235 A2Testpropanespherical burner85%stream110 kPaflow terminated
21235 C1Testpropanespherical burner50%stream110 kPaflow terminated
21235 F1Testpropanespherical burner21%stream110 kPaflow terminated
21235 F2Testpropanespherical burner21%stream110 kPadid not ignite
21235 H1Testpropanespherical burner18%stream110 kPaself-extinguished
21235 J1Testpropanespherical burner19%stream110 kPaflow terminated
21235 B1Testpropanespherical burner85%stream110 kPaflow terminated
21235 K1Testpropanespherical burner85%stream55.2 kPaflow terminated
21235 L1Testpropanespherical burner85%stream55.2 kPaflow terminated
21242 A1Testpropanespherical burner85%stream55.2 kPaflow terminated
21242 P1Testpropanespherical burner30%stream55.2 kPaflow terminated
21242 F2Testpropanespherical burner21%stream55.2 kPadid not ignite
21242 F3Testpropanespherical burner21%stream55.2 kPadid not ignite
21242 F4Testpropanespherical burner21%stream55.2 kPadid not ignite
21242 P2Testpropanespherical burner30%stream55.2 kPadid not ignite
21256 A1Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 A2Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 A3Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 A4Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 A5Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 C1Testn-butanespherical burner50%stream221 kPaself-extinguished
21256 F1Testn-butanespherical burner21%stream221 kPaflow terminated
21256 B1Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 C2Testn-butanespherical burner50%stream221 kPaself-extinguished
21256 H1Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 H2Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 H3Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 H4Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 H5Testn-butanespherical burner85%stream221 kPaself-extinguished
21256 K1Testn-butanespherical burner50%stream221 kPaself-extinguished
21256 M1Testn-butanespherical burner21%stream221 kPaself-extinguished
21256 J1Testn-butanespherical burner85%stream221 kPaself-extinguished
21265 A1Testn-butanespherical burner85%stream331 kPaself-extinguished
21265 A2Testn-butanespherical burner85%stream331 kPaself-extinguished
21265 A3Testn-butanespherical burner85%stream331 kPaself-extinguished
21265 A4Testn-butanespherical burner85%stream331 kPaself-extinguished
21265 A5Testn-butanespherical burner85%stream331 kPaself-extinguished
21265 C1Testn-butanespherical burner50%stream331 kPaself-extinguished
21265 C2Testn-butanespherical burner50%stream331 kPaself-extinguished
21265 C3Testn-butanespherical burner50%stream331 kPaself-extinguished
21265 F1Testn-butanespherical burner21%stream331 kPaself-extinguished
21265 F2Testn-butanespherical burner21%stream331 kPaflow terminated
21265 F3Testn-butanespherical burner21%stream331 kPadid not ignite
21265 F4Testn-butanespherical burner21%stream331 kPadid not ignite
21265 H1Testn-butanespherical burner40%stream331 kPaself-extinguished
21265 H2Testn-butanespherical burner40%stream331 kPaflow terminated
21265 J1Testn-butanespherical burner70%stream331 kPaself-extinguished
21265 K1Testn-butanespherical burner45%stream331 kPaself-extinguished
21265 H3Testn-butanespherical burner40%stream331 kPaflow terminated
21270 A1Testn-butanespherical burner85%stream110 kPaflow terminated
21270 A2Testn-butanespherical burner85%stream110 kPaflow terminated
21270 A3Testn-butanespherical burner85%stream110 kPaflow terminated
21270 A4Testn-butanespherical burner85%stream110 kPaflow terminated
21270 C1Testn-butanespherical burner50%stream110 kPaflow terminated
21270 H1Testn-butanespherical burner85%stream110 kPaself-extinguished
21270 H2Testn-butanespherical burner85%stream110 kPaflow terminated
21270 H3Testn-butanespherical burner85%stream110 kPaflow terminated
21270 H4Testn-butanespherical burner85%stream110 kPaflow terminated
21270 H5Testn-butanespherical burner85%stream110 kPaself-extinguished
21277 A1Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 H1Testn-butanespherical burner50%stream55.2 kPaflow terminated
21277 J1Testn-butanespherical burner21%stream55.2 kPadid not ignite
21277 K1Testn-butanespherical burner30%stream55.2 kPadid not ignite
21277 K2Testn-butanespherical burner30%stream55.2 kPaflow terminated
21277 J2Testn-butanespherical burner21%stream55.2 kPadid not ignite
21277 C1Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 C2Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 L1Testn-butanespherical burner50%stream55.2 kPaflow terminated
21277 F1Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 F2Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 M1Testn-butanespherical burner85%stream55.2 kPaflow terminated
21277 N1Testn-butanespherical burner50%stream55.2 kPaflow terminated
21277 P1Testn-butanespherical burner30%stream55.2 kPaflow terminated
21088A1Testethanespherical burner39.4%94.4 kPaself-extinguished
21088 B1Testethanespherical burner39%94.4 kPaself-extinguished
21088 C1Testethanespherical burner38.6%94.4 kPaself-extinguished
21088 D1Testethanespherical burner38.3%94.4 kPaflow terminated
21088 F1Testethanespherical burner38%94.4 kPaflow terminated
21088 G1Testethanespherical burner38%94.4 kPaself-extinguished
21088 H1Testethanespherical burner37.6%94.4 kPaflow terminated
21088 J1Testethanespherical burner37.3%94.4 kPaself-extinguished
21088 K1Testethanespherical burner37%94.4 kPaflow terminated
21088 H2Testethanespherical burner36.5%94.4 kPaflow terminated
21088 M4Testethanespherical burner21%101 kPaself-extinguished
21088 L1Testethanespherical burner21%101 kPaself-extinguished
21088 N1Testethanespherical burner18%101 kPaself-extinguished
21088 P1Testethanespherical burner18%101 kPaself-extinguished
21102A1Testn-butanespherical burner39.6%101 kPaself-extinguished
21102 C1Testn-butanespherical burner39.3%101 kPaself-extinguished
21102 B1Testn-butanespherical burner39.1%101 kPaself-extinguished
21102 C2Testn-butanespherical burner38.8%101 kPaflow terminated
21102 C3Testn-butanespherical burner38.6%101 kPaself-extinguished
21102 C4Testn-butanespherical burner38.3%101 kPadid not ignite
21102 C5Testn-butanespherical burner38.3%101 kPaflow terminated
21102 C6Testn-butanespherical burner38.1%101 kPadid not ignite
21102 C7Testn-butanespherical burner38.1%101 kPaflow terminated
21102 C8Testn-butanespherical burner38.1%101 kPadid not ignite
21102 M1Testn-butanespherical burner23.4%101 kPaself-extinguished
21102 M2Testn-butanespherical burner23.4%101 kPaself-extinguished
21102 M3Testn-butanespherical burner23.3%101 kPadid not ignite
21102 M4Testn-butanespherical burner23.3%101 kPadid not ignite
21102 M5Testn-butanespherical burner23.3%101 kPadid not ignite
21102 M6Testn-butanespherical burner23.3%101 kPadid not ignite
21106A4Testn-butanespherical burner39.3%50.7 kPaself-extinguished
21106 B1Testn-butanespherical burner38.5%50.7 kPaself-extinguished
21106 C1Testn-butanespherical burner37.7%50.7 kPaself-extinguished
21106 D1Testn-butanespherical burner36.9%50.7 kPaself-extinguished
21106 F1Testn-butanespherical burner35.9%50.7 kPaflow terminated
21106 F2Testn-butanespherical burner35.4%50.7 kPadid not ignite
21106 F3Testn-butanespherical burner35.4%50.7 kPaflow terminated
21106 F4Testn-butanespherical burner35.4%50.7 kPaflow terminated
21106 F5Testn-butanespherical burner35.3%50.7 kPadid not ignite
21106 G6Testn-butanespherical burner21%50.7 kPaself-extinguished
21106 G7Testn-butanespherical burner20.9%50.7 kPaself-extinguished
21106 G9Testn-butanespherical burner20.7%50.7 kPaself-extinguished
21106 H1Testn-butanespherical burner20.7%50.7 kPadid not ignite
21106 H2Testn-butanespherical burner20.7%50.7 kPadid not ignite
21112A1Testpropanespherical burner39.5%94.4 kPaflow terminated
21112 A2Testpropanespherical burner39.4%94.4 kPaself-extinguished
21112 A3Testpropanespherical burner39.1%94.4 kPaself-extinguished
21112 A4Testpropanespherical burner38.7%94.4 kPaflow terminated
21112 A5Testpropanespherical burner38%94.4 kPaself-extinguished
21112 C1Testpropanespherical burner37.8%94.4 kPaflow terminated
21112 C2Testpropanespherical burner37.7%94.4 kPaflow terminated
21112 A6Testpropanespherical burner37.7%94.4 kPaself-extinguished
21112 C3Testpropanespherical burner36.6%94.4 kPadid not ignite
21112 C4Testpropanespherical burner36.6%94.4 kPadid not ignite
21112 C5Testpropanespherical burner36.6%94.4 kPadid not ignite
21112 C6Testpropanespherical burner36.6%94.4 kPadid not ignite
21112 F1Testpropanespherical burner21.3%101 kPadid not ignite
21112 F2Testpropanespherical burner21.3%101 kPaself-extinguished
21112 F3Testpropanespherical burner21.2%101 kPaself-extinguished
21112 F4Testpropanespherical burner21.2%101 kPaself-extinguished
21112 F5Testpropanespherical burner21.2%101 kPadid not ignite
21112 H1Testpropanespherical burner21.2%101 kPaself-extinguished
21112 H2Testpropanespherical burner21.2%101 kPaself-extinguished
21112 H3Testpropanespherical burner21.1%101 kPadid not ignite
21125A1Testn-butanespherical burner39.5%101 kPadid not ignite
21125 A2Testn-butanespherical burner39.5%101 kPaself-extinguished
21125 A3Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A4Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A5Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A6Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A7Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A8Testn-butanespherical burner39.4%101 kPadid not ignite
21125 A9Testn-butanespherical burner39.4%101 kPadid not ignite
21125 H1Testn-butanespherical burner39.4%101 kPadid not ignite
21125 H2Testn-butanespherical burner39.4%101 kPadid not ignite
21125 H3Testn-butanespherical burner39.4%101 kPadid not ignite
21125 H4Testn-butanespherical burner39.4%101 kPadid not ignite
21125 J1Testn-butanespherical burner39.4%101 kPadid not ignite
21125 H5Testn-butanespherical burner39.4%101 kPadid not ignite
21125 K1Testn-butanespherical burner39.4%101 kPaself-extinguished
21125 K2Testn-butanespherical burner38.9%101 kPaself-extinguished
21125 K3Testn-butanespherical burner38.4%101 kPaflow terminated
21125 D1Testn-butanespherical burner21.1%101 kPaself-extinguished
21125 D2Testn-butanespherical burner21.1%101 kPaself-extinguished
21125 D3Testn-butanespherical burner21.1%101 kPadid not ignite
21125 D4Testn-butanespherical burner21.1%101 kPadid not ignite
21125 D5Testn-butanespherical burner21.1%101 kPadid not ignite
21125 D6Testn-butanespherical burner21.1%101 kPadid not ignite
21130A1Testpropanespherical burner21.1%203 kPaself-extinguished
21130 A2Testpropanespherical burner21.1%203 kPaself-extinguished
21130 A3Testpropanespherical burner21.1%203 kPadid not ignite
21130 A4Testpropanespherical burner21.1%203 kPadid not ignite
21130 A5Testpropanespherical burner21.1%203 kPaself-extinguished
21130 A6Testpropanespherical burner21.1%203 kPadid not ignite
21130 A7Testpropanespherical burner21.1%203 kPadid not ignite
21130 A8Testpropanespherical burner21.1%203 kPadid not ignite
21130 A9Testpropanespherical burner21.1%203 kPaself-extinguished
21130 M1Testpropanespherical burner21.1%203 kPaself-extinguished
21130 M2Testpropanespherical burner21.1%203 kPaself-extinguished
21130 M3Testpropanespherical burner21%203 kPaself-extinguished
21130 G1Testpropanespherical burner21.7%304 kPadid not ignite
21130 G2Testpropanespherical burner21.7%304 kPaself-extinguished
21130 G3Testpropanespherical burner21.7%304 kPaself-extinguished
21130 G4Testpropanespherical burner21.7%304 kPadid not ignite
21130 G5Testpropanespherical burner21.7%304 kPadid not ignite
21130 G6Testpropanespherical burner21.7%304 kPaself-extinguished
21130 G7Testpropanespherical burner21.7%304 kPaself-extinguished
21130 N1Testpropanespherical burner21.7%304 kPaself-extinguished
21130 N2Testpropanespherical burner21.7%304 kPaself-extinguished
21130 N3Testpropanespherical burner21.6%304 kPaself-extinguished
21130 N4Testpropanespherical burner21.6%304 kPaself-extinguished
21130 N5Testpropanespherical burner21.6%304 kPadid not ignite
21137A1Testpropanespherical burner40%101 kPaself-extinguished
21137 A2Testpropanespherical burner39.7%101 kPaself-extinguished
21137 A3Testpropanespherical burner39.5%101 kPaself-extinguished
21137 B1Testpropanespherical burner39%101 kPaflow terminated
21137 B2Testpropanespherical burner37.1%101 kPaflow terminated
21137 A4Testpropanespherical burner35.7%101 kPaself-extinguished
21137 A5Testpropanespherical burner35.6%101 kPaself-extinguished
21137 A6Testpropanespherical burner35.4%101 kPaself-extinguished
21137 A7Testpropanespherical burner35.2%101 kPaself-extinguished
21137 D1Testpropanespherical burner21%101 kPaself-extinguished
21137 D2Testpropanespherical burner20.9%101 kPaself-extinguished
21137 C1Testpropanespherical burner20.9%101 kPaself-extinguished
21153A1Testethanespherical burner38.9%50.7 kPaself-extinguished
21153 A2Testethanespherical burner37.6%50.7 kPaself-extinguished
21153 A3Testethanespherical burner36.4%50.7 kPaself-extinguished
21153 F1Testethanespherical burner34.1%50.7 kPaself-extinguished
21153 A4Testethanespherical burner33.5%50.7 kPaflow terminated
21153 A5Testethanespherical burner33.2%50.7 kPaflow terminated
21153 C1Testethanespherical burner39.9%203 kPaself-extinguished
21153 C2Testethanespherical burner39.7%203 kPaself-extinguished
21153 C3Testethanespherical burner39.5%203 kPaself-extinguished
21153 G1Testethanespherical burner39.2%203 kPaself-extinguished
21153 C4Testethanespherical burner38.9%203 kPaflow terminated
21153 C5Testethanespherical burner38.4%203 kPaflow terminated
21153 C6Testethanespherical burner38.4%203 kPaself-extinguished
21153 C7Testethanespherical burner38.2%203 kPaflow terminated
21162A1Testethanespherical burner40%101 kPaself-extinguished
21162 A2Testethanespherical burner39.5%101 kPaself-extinguished
21162 A3Testethanespherical burner39%101 kPaself-extinguished
21162 B1Testethanespherical burner37.9%101 kPaself-extinguished
21162 A4Testethanespherical burner37.2%101 kPaself-extinguished
21162 C1Testethanespherical burner21%101 kPaself-extinguished
21162 C2Testethanespherical burner21%101 kPaself-extinguished
21162 C3Testethanespherical burner20.9%101 kPaself-extinguished
21162 C4Testethanespherical burner20.9%101 kPaself-extinguished
21162 C5Testethanespherical burner20.8%101 kPaself-extinguished
21162 D1Testethanespherical burner20.8%101 kPaself-extinguished
21162 F1Testethanespherical burner20.7%101 kPadid not ignite
21162 F2Testethanespherical burner20.7%101 kPaself-extinguished
21174 A1Testn-butanespherical burner38.9%50.7 kPaself-extinguished
21174 A2Testn-butanespherical burner38.3%50.7 kPaself-extinguished
21174 A3Testn-butanespherical burner37.9%50.7 kPaself-extinguished
21174 A4Testn-butanespherical burner37.2%50.7 kPaself-extinguished
21174 B1Testn-butanespherical burner35.5%50.7 kPaself-extinguished
21174 C1Testn-butanespherical burner39.9%203 kPaself-extinguished
21174 C2Testn-butanespherical burner39.7%203 kPaself-extinguished
21174 C3Testn-butanespherical burner39.5%203 kPaself-extinguished
21174 C4Testn-butanespherical burner39.4%203 kPaself-extinguished
21174 D1Testn-butanespherical burner39.2%203 kPaself-extinguished
21174 F1Testn-butanespherical burner39.1%203 kPaself-extinguished
21174 C5Testn-butanespherical burner39%203 kPaflow terminated
21174 C6Testn-butanespherical burner38.9%203 kPaself-extinguished
21174 F2Testn-butanespherical burner38.5%203 kPaflow terminated
21174 F3Testn-butanespherical burner38.5%203 kPaflow terminated
21174 F4Testn-butanespherical burner38.4%203 kPaflow terminated
21291 A1Testn-butanespherical burner39.9%203 kPaflow terminated
21291 C1Testn-butanespherical burner39.4%203 kPaflow terminated
21291 C2Testn-butanespherical burner38.9%203 kPaself-extinguished
21291 B1Testn-butanespherical burner38.8%203 kPaself-extinguished
21291 H1Testn-butanespherical burner38.7%203 kPaself-extinguished
21291 H2Testn-butanespherical burner38.6%203 kPaflow terminated
21291 D1Testn-butanespherical burner39.8%101 kPaself-extinguished
21291 G1Testn-butanespherical burner39.5%101 kPaself-extinguished
21291 G2Testn-butanespherical burner38.8%101 kPaself-extinguished
21291 J1Testn-butanespherical burner38.5%101 kPaflow terminated
21291 J2Testn-butanespherical burner38.3%101 kPaself-extinguished
21291 J3Testn-butanespherical burner38.1%101 kPaself-extinguished
How the table was read, and what was repaired

CFI-G - inverse flames

PSI-159_Experimental table_CFI-G_Inverse Flames.csv

154 rows in the file, 154 kept as records.

sha256 d4d44f8b9896936728748e34d1b6ad0812032a92fa5289599b708c138e3a9b39 · fetched 2026-11-11

CFI-G - normal flames

PSI-159_Experimental table_CFI-G_Normal Flames.csv

179 rows in the file, 179 kept as records.

sha256 d95a621c3fbd27d204dd32ed29fa17d68f2b779d6a523cde8479ed7ebaa5251a · fetched 2026-11-11

NASA's description

Objectives

1. Plan and support flight testing on the International Space Station (ISS). 2. Determine the conditions for which cool diffusion flames occur for propane, n-butane, and n-pentane; normal and inverse flames; and a broad range of Zst, Tad, and fluent flow rate. 3. Support the flight tests with advanced CFD simulations. 4. Identify or develop a chemical kinetics mechanism that yields good agreement between the CFD predictions and the ISS measurements. 5. Disseminate the results as widely as possible.

Approach

Perform spherical diffusion flame tests aboard the International Space Station. Consider multiple fuels, a range of reactant dilutions, flow rates, and pressures for normal and inverse convection directions. Observe the flames with a broad suite of cameras, radiometers, photomultiplier tubes, and thermocouples.

Hypothesis

The hypotheses of this research are that testing aboard the ISS can demonstrate the following for the first time, contributing to an improved understanding of cool flame kinetics. 1. Steady-state cool diffusion flames on spherical porous burners. 2. Cool diffusion flames burning propane, n-butane, and n-pentane. 3. Cool diffusion flames for a wide range of Zst, Tad, and pressures. 4. Inverse cool diffusion flames. 5. Cool diffusion flames for which a decrease in fluent flow rate will cause extinction, whereas an increase will cause a transition to a hot diffusion flame, with oscillation possible between hot and cool flames.

Research impacts and Earth benefits

Combustion provides 86% of the world’s energy and an even higher fraction of the energy used for transportation. The internal combustion engines used for transportation generally have thermal efficiencies of 38% or lower because of thermal losses. These efficiencies may increase to 60% if future engines can take advantage of ultra-lean combustion. However, this progress is being impeded by the limited understanding of the chemistry of cool flames. Research into cool diffusion flames (whose peak temperatures are 500 – 1000 K) has grown exponentially since they were discovered in 2012. The measurements performed for this project will help to test and advance cool flame kinetics mechanisms. This should facilitate the development of more efficient internal combustion engines.

Publications

2 listed in PSI, 2 with a DOI.

  1. Spherical gas-fueled cool diffusion flamesKim Minhyeng, Waddell Kendyl A., Sunderland Peter B., Nayagam Vedha, Stocker Dennis P., Dietrich Daniel L., Ju Yiguang, Williams Forman A., Irace Phillip, Axelbaum Richard L.
  2. Cool diffusion flames in a stably stratified stagnation flowWaddell Kendyl A., Lee Han Ju, Nayagam Vedha, Axelbaum Richard L., Sunderland Peter B.

Hardware and raw data

2.1 TB of raw data on PSI: reports 1, raw data 3,749, metadata 1, experimental table 2, engineering documents 1, representative image(s) 2. FlameLens reads the experimental table, not the raw video or sensor files.

On Earth

Cleaner combustion: Cool-flame kinetics for more efficient, ultra-lean engines.

“This should facilitate the development of more efficient internal combustion engines.”