Fractal Geometry Application in Estimation of Turbulent Burning Velocity of Wrinkled Laminar Flame

Abstract

In the present study, the unburned gas region of wrinkled laminar flame stabilized on a Bunsen burner was visualized by a laser tomography and the fractal analysis was applied to the flame boundaries to characterize the geometry of wrinkled laminar flame. The effects of mixture turbulence, laminar burning velocity and burner geometry on the fractal parameters were examined statistically. The fractal dimension D₃ was found to be expressed by non-dimensional parameter u’/S_L, and to increase with the turbulence intensity from 2.17 to 2.32, approaching asymptotically to 2.36. Inner and outer cutoff scales are not directly correlated with typical turbulence scales of unburned mixture. The inner cutoff scale £, is affected by the flame properties as well as the turbulence characteristics. For the Bunsen burner flames, the outer cutoffscale ϵ_i was found to be determined by the flame base diameter. The turbulent burning velocity can be estimated approximately by the equation, S_T/S_L = (ϵ_i/ ϵ_o,)^2−D₂

Key Words:

• Turbulent combustion
• wrinkled laminar flame
• fractal
• turbulent burning velocity

Additional information

Notes on contributors

A. YOSHIDA

Correspondence should be sent to the first author.