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Studies of Premixed-gas Flames at Microgravity

Gravity affects flames through buoyancy-induced natural convection. Prof. Ronney has conducted experiments on flames at low gravity, obtained in drop towers and aircraft flying parabolic trajectories, since 1981. These experiments have demonstrated a variety of new phenomena which are "masked" at earth gravity due to buoyancy. Most seem to result from interactions between radiant heat loss, unequal rates of diffusion of thermal energy and reactants (i.e. Lewis number effects), and flame front curvature and stretch. Such studies are relevant to spacecraft fire safety applications and the development of clean, lean-burning combustion engines on earth.

One of the most remarkable findings of these experiments is the discovery of "flame balls," which are stable, stationary, spherically symmetric flames that occur in combustible gas mixtures having low Lewis number (ratio of thermal diffusivity of the bulk mixture to the mass diffusivity of the stoichiometrically limiting reactant). An experiment entitled "Structure Of Flame Balls At Low Lewis-number," or "SOFBALL" was performed on the MSL-1 Space Shuttle mission , April 4 - 8, 1997 and the reflight of this mission, STS-94/MSL-1R, July 1 - 16, 1997. Prof. Ronney served as the Alternate Payload Specialist Astronaut for both missions. These experiments used a combustion apparatus, called CM-1, developed by NASA-Glenn.

Short description of the results from the SOFBALL experiments 
Some pictures of flame balls in space 
View on-line presentation about SOFBALL results 
Much longer, more detailed text-based version 
Information about the CM-1 experimental facility 
Download .pdf version of AIAA Journal paper (2.4 MB) 
Download Powerpoint presentation on SOFBALL (810 KB) 
Download entire set of SOFBALL movies and powerpoint presentation engine (30 MB!) 

A reflight of this experiment is scheduled using the Combustion Module-2 facility for STS-107 in January 2001 to complete the test matrix and test the new hypotheses developed based on the results from the MSL-1 missions.

 In addition, we are studying the effects of radiation in the "optically thick" regime, where reabsorption of emitted photons cannot be neglected. This regime can be studied through the use of different gas mixtures, pressures and the addition of inert solid particles. Under optically thick conditions, theory predicts that flame propagation rates can be increased over those of non-absorbing mixtures. Our µg experiments have indeed demonstrated this effect. 

Radiation effects of premixed-gas flames (on-line version) 
Download .pdf version of paper (3.1 MB) 
Download powerpoint presentation (504 KB) 

Publications 
Abid, M., Wu, M. S., Liu, J. B., Ronney, P. D., Ueki, M., K. Maruta, K., Kobayashi , H., Niioka, T. and VanZandt, D. M., "Experimental and Numerical Study of Flame Ball IR and UV Emissions," Combustion and Flame, Vol. 116, pp. 348-359 (1999).

Wu, M. S., Ronney, P. D., Colantonio, R., VanZandt, D., "Detailed Numerical Simulation of Flame Ball Structure and Dynamics," Combustion and Flame, Vol. 116, pp. 387-397(1999).

Wu, M.-S., Liu, J. B. and Ronney, P. D., "Numerical Simulation of Diluent Effects on Flame Ball Structure and Dynamics," Twenty-Seventh Symposium (International) on Combustion, Combustion Institute, Pittsburgh, 1998, pp. 2543-2550.

Ju, Y., Masuya, G. and Ronney, P. D., "Effects of Radiative Emission and Absorption on the Propagation and Extinction of Premixed Gas Flames" Twenty-Seventh International Symposium on Combustion, Combustion Institute, Pittsburgh, 1998, pp. 2619-2626. 

View on-line version
Download .pdf version (3.1 MB)
Download powerpoint presentation (504 KB)

Buckmaster, J. D. and Ronney, P. D., "Flame Ball Drift in the Presence of a Total Diffusive Heat Flux," Twenty-Seventh International Symposium on Combustion, Combustion Institute, Pittsburgh, 1998, pp. 2603-2610. Ronney, P. D., "Understanding Combustion Processes Through Microgravity Research," Twenty-Seventh International Symposium on Combustion, Combustion Institute, Pittsburgh, 1998, pp. 2485-2506 (invited paper). 

View on-line version
Download .pdf version (8.7 MB)
Download powerpoint presentation (2.4 MB)

Ronney, P. D., "Premixed Laminar and Turbulent Flames at Microgravity," Space Forum, Vol. 4, pp. 49-98 (1998). Ronney, P. D., Wu, M. S., Weiland, K. J. and Pearlman, H. G., "Flame Ball Experiments in Space: Preliminary Results from STS-83," AIAA Journal, Vol. 36, pp. 1361-1368 (1998).

View on-line version
Download .pdf version (2.4 MB)
Download powerpoint presentation (810 KB)
Download entire set of SOFBALL movies and powerpoint presentation engine (30 MB!)

Pearlman, H. G., Ronney, P. D., "Near-Limit Behavior of High Lewis-Number Premixed Flames in Tubes at Normal and Low Gravity," Physics of Fluids, Vol. 6, pp. 4009-4018 (1994). Pearlman, H. G., Ronney, P. D., "Self-Organized Spiral and Circular Waves in Premixed Gas Flames," Journal of Chemical Physics, Vol. 101, pp. 2632-2633 (1994). Lozinski, D., Buckmaster, J. D., Ronney, P. D., "Absolute Flammability Limits and Flame Balls in Optically Thick Mixtures," Combustion and Flame, Vol. 97, pp. 301-316 (1994).

Ronney, P. D., Whaling, K. N., Abbud-Madrid, A., Gatto, J. L., Pisowicz, V. L., "Stationary Premixed Flames in Spherical and Cylindrical Geometries," AIAA Journal, Vol. 32, pp. 569-577 (1994).

Abbud-Madrid, A., Ronney, P. D., "Premixed Flame Propagation in an Optically-Thick Gas," AIAA Journal, Vol. 31, pp. 2179-2181 (1993).

Buckmaster, J. B., Gessman, R., Ronney, P. D., "The Three-Dimensional Dynamics of Flame Balls," Twenty-Fourth International Symposium on Combustion, Combustion Institute, Pittsburgh, 1992, pp. 53-59.

 Buckmaster, J. D., Joulin, G., Ronney, P. D., "Structure and Stability of Non-adiabatic Flame Balls: II. Effects of Far-Field Losses," Combustion and Flame, Vol. 84, pp. 411-422 (1991). Abbud-Madrid, A., Ronney, P. D., "Effects of Radiative and Diffusive Transport Processes on Premixed Flames Near Flammability Limits," Twenty Third Symposium (International) on Combustion, Combustion Institute, 1990, pp. 423-431.

Farmer, J. N., Ronney, P. D., "A Numerical Study of Unsteady Nonadiabatic Flames," Combustion Science and Technology, Vol. 73, pp. 555-574 (1990). 

Ronney, P. D., "Near-Limit Flame Structures at Low Lewis Number," Combustion and Flame, Vol. 82, pp. 1-14 (1990).

Buckmaster, J. D., Joulin, G., Ronney, P. D., "Effects of Heat Loss on the Structure and Stability of Flame Balls," Combustion and Flame, Vol. 79, pp. 381-392 (1990).

Ronney, P. D., Sivashinsky, G. I., "A Theoretical Study of Propagation and Extinction of Nonsteady Spherical Flame Fronts," SIAM Journal on Applied Mathematics, Vol. 49, pp. 1029-1046 (1989).

Ronney, P. D., "On the Mechanisms of Flame Propagation Limits and Extinction Processes at Microgravity," Twenty Second Symposium (International) on Combustion, Combustion Institute, 1988, pp. 1615-1623.

Ronney, P. D., "Effect of Chemistry and Transport Properties on Near-Limit Flames at Microgravity," Combustion Science and Technology, Vol. 59, pp. 123-141 (1988). Ronney, P. D., "Effect of Gravity on Halocarbon Flame Retardant Effectiveness," Acta Astronautica, Vol. 12, pp. 915-921 (1985).

Ronney, P. D., "Effect of Gravity on Laminar Premixed Gas Combustion II: Ignition and Extinction Phenomena," Combustion and Flame, Vol. 62, pp. 120-132 (1985).

Ronney, P. D., Wachman, H. Y., "Effect of Gravity on Laminar Premixed Gas Combustion I: Flammability Limits and Burning Velocities," Combustion and Flame, Vol. 62, pp. 107-119 (1985).