Facets of the Propagation of Lean Laminar Premixed Polydisperse Spray Flames

Abstract

A new numerical study of the multifaceted unsteady propagation of lean laminar premixed polydisperse spray flames in a two-dimensional channel is presented. The impact of the spray's initial droplet size distribution on the flame propagation is investigated for two very different initial size distributions having the same Sauter mean diameter. It is found that the initial droplet size distribution can exert a strong influence on the average flame speed, spatial instabilities, and timewise oscillations and conditions for their onset. In addition, even for the same size distribution, the actual mode of flame propagation is influenced by the initial perturbation and, here, was shown to be attracted to one of two unsteady limiting modes.

Keywords:

• Flame propagation
• Polydisperse lean spray
• Premixed spray
• Stability

ACKNOWLEDGMENTS

LSK and GIS gratefully acknowledge the support of the US–Israel Binational Science Foundation (Grant 2006-151), the Israel Science Foundation (Grants 32/09). JBG thanks the Technion Fund for the Promotion of Research, the Lady Davis Chair in Aerospace Engineering, and the US–Israel Binational Science Foundation (Grant 2004-069) for supporting this research.

Notes

¹We assume that at each point (x, y), the temperature T(t, x, y) increases monotonically with time t.