Team idea · interactive

Flame Lab

Drag the controls and watch the flame respond. Shape, colour and whether it survives come from rules written from the 24 briefs — every rule shows its source below. Illustrative model, not a CFD simulation.

airflow → flame spreads with the flow

PMMA (acrylic)

O₂ 21.0 %

g 0.00 · Microgravity

v 10.0 cm/s

P 101 kPa

Burning

Colour

Yellow-orange with blue base

Shape

Hemispherical

Material

PMMA (acrylic)

Gravity

Microgravity

Same O₂, flow, pressure and material on both sides

Material

Oxygen21.0%

Gravity0.00g

Forced airflow10.0cm/s

Cabin pressure101kPa

Spread direction

Oxygen vs limiting oxygen+7.4 %

10 %limit 13.6 %40 %

Why the flame looks like this

Rules applied for the current settings. Data rules quote a brief; assumption rules fill gaps and are labelled.

Microgravity: no buoyancy, oxygen arrives by diffusion and ventilation → rounder, dimmer, bluer, steady flame.
Show quote
“Candle flame in normal gravity is tear-drop-like shape and bright yellow color, however in microgravity it becomes spherical (or hemispherical) and dim blue respectively.”
Buoyant flow ≈ 17 cm/s at 1 g, scaled with gravity and pressure → 0.0 cm/s here.
Show quote
“To account for the additional inherent buoyant stretch, the normal gravity boundary was empirically shifted to the right by a value ab = 80 s-1, which for the base rod size corresponds to a forced flow velocity of 17 cm/s, in good agreement with buoyant flow velocity estimates.”
Limiting O₂ in µg with airflow: 13.6 % (vs 16 % in 1g).
Show quote
“The 1g blowoff for the ¼” rod is at 16% oxygen, whereas we obtained steady spreading at 13.6% oxygen in BASS-II. Thus the material has a negative Oxygen Margin of Safety of 2.4% O2, and the normal gravity flammability limits should be de-rated by at least that much.”
With ventilation the flame lengthens downstream and gets brighter; at a few cm/s it becomes sooty.
Show quote
“During PMMA combustion, the flame is white at V > 1 cm/s, due to the presence of soot particles, and it becomes dark-blue and almost invisible at V = 0.75 to 0.5.”

How to read it. Blue means little soot and a cooler flame; yellow-white means soot glowing. In microgravity the flame is fed only by diffusion and the cabin airflow, so it turns round and blue, and dies if the airflow drops below the limiting velocity.

Limits of this model. Partial-gravity limits for PMMA and thin fuels are interpolated (no data). Buoyant flow is assumed ≈ 17 cm/s × g. Ghost flames mark combinations the sources do not cover.

Try this

ISS cabin → drag airflow below 0.5 cm/s: the flame dies (that is why the ISS shuts the fans off).
PMMA at 14 % O₂: no flame on Earth, but it burns in microgravity.
Mars, Getinax: safe up to 23 % O₂, though it burns on Earth above 19 %.
Thin sheet, opposed flow, 40 kPa: the low-pressure limit is sudden.