1. Effect of Variable Gravity on Premixed Turbulent Flames
Mark Ratner

2. Premixed Flames in Microgravity
Allows the studying of phenomena in flames usually obscured by the effects of buoyancy
Combustion in microgravity has been shown to alter flame characteristics like flammability limits, flame stability, and flame speeds
Different flame geometries observed at microgravity, e.g. “flame balls”
Spherical “flame balls” are only observed in microgravity due to lack of buoyancy effect
“Flame balls” drift in microgravity due to enthalpy gradients cause by nearby neighbors

3. Premixed Flames in Microgravity
Turbulent Flame surface wrinkling a strong function of effective gravity
Different heat transfer mechanisms present in microgravity than at high/Earth gravity
Heat transfer due to convection/buoyancy effects are minimized
Radiation and conduction are primary mechanisms of heat transfer
Low gravity tends to allow flame to break apart to break into a cellular structure

4. Results: mass flow = .1kg/s
G=10-3G0
G=10-2G0
G=G0
G=10G0

5. Results: mass flow = .25kg/s
G=10-3G0
G=10-2G0
G=G0
G=10G0

6. Results: mass flow = .5kg/s
G=10-3G0
G=10-2G0
G=G0
G=10G0

7. Results: Summary
Flame height clearly proportional to total mass flow rate of Methane/Air mixture
Flame wrinkling is most dramatic at low effective gravity
Increased gravity suppresses flame wrinkling
Decreasing gravity increases the average flame height due to the increased wrinkling effect

8. Future Work
Vary the type of fuel in order to vary energy content and density of the mixture
Vary the incoming fuel mixture to allow for partially premixed and non-premixed flames
Allow for gravity to be in the opposite direction to observe more significant flame stretching effects