Graduate Students: Tarek Ahmed (Ph. D.’95), Kent D. Kasper (M. S. ’95), Yan Dong (M.S. ’99)

Project Summary

This research is aimed at an in-depth understanding of buoyant plume instabilities in non-reacting plumes (helium and helium/air mixtures) as well as buoyant diffusion flames. The pulsatile instability in the buoyant regime exhibits itself as periodic oscillations of the plume boundaries near the source of a plume, leading to formation of large scale vortical structures which convect through the plume affecting its dynamics and entrainment characteristics. Our experimental research is focused on the identification and correlation of the limits of the oscillatory regime, characterization and correlation of pulsation frequencies and plume behavior under external periodic forcing. Additionally, computational simulations of the unsteady behavior of planar and axisymmetric buoyant plumes are being carried out using the Lagrangian vortex element technique in collaboration with Prof. Marios Soteriou’s research group. Some sample images of buoyant non-reacting plumes (unforced planar, unforced axisymmetric, forced axisymmetric) and unforced buoyant axisymmetric diffusion flames are shown

Unsteady behavior of an axisymmetric helium plume

Buoyant Plume Instabilities

Planar Helium Plume Axisymmetric Helium Plume Axisymmetric Helium Plume forced at 5 Hz

Buoyant Flame Instabilities Varicose Instability in a Buoyant Propane Flame Sinuous Instability in a Buoyant Propane Flame Same Flame Stabilized in a O2/He Atmosphere

Publications

Soteriou, M. C., Dong, Y. and Cetegen, B. M., “Lagrangian simulation of the unsteady near field dynamics of planar buoyant plumes”, Physics of Fluids , Vol. 14, No. 9, pp. 3118-3140, 2002

Cetegen, B. M. and Dong, Y., “Experiments on instability modes of buoyant diffusion flames and effects of ambient atmosphere on instabilities”, Experiments in Fluids, Vol. 28 (6), pp.546-558, 2000

Cetegen, B. M., “Integral analysis of planar and axisymmetric steady laminar buoyant diffusion flames”, Combustion Theory and Modeling, Vol. 3, pp.13-32, 1999

Cetegen, B. M., “A phenomenological model for near-field fire plume entrainment”, Fire Safety Journal, Vol. 31, pp. 299 – 312, 1998

Cetegen, B. M., Dong, Y., and Soteriou, M. C., “Experiments on stability and oscillatory behavior of planar buoyant plumes”, Physics of Fluids, Vol. 10, No. 7, pp. 1658 – 1665, 1998

Cetegen, B. M., “Behavior of naturally oscillating and periodically forced axisymmetric buoyant plumes of helium and helium-air mixtures”, Physics of Fluids, Vol. 9. No. 12 , pp. 3742-3753, 1997

Cetegen, B. M., “Measurements of Instantaneous Velocity Field of a Nonreacting Pulsating Buoyant Plume by Particle Image Velocimetry”, Combustion Science and Technology, Vol. 123,:1-6, p. 377, 1997.

Cetegen, B. M. and Kasper, K. D., “Experiments on the Oscillatory Behavior of Buoyant Plumes of Helium and helium/Air Mixtures”, Physics of Fluids, Vol. 8 (11), pp. 2974-2984, 1996.

Cetegen, B. M. and Ahmed, T., “Experiments on the Periodic Instability of Buoyant Plumes and Pool Fires”, Combustion & Flame,Vol.93, pp.157-184 , 1993