Dynamical Relationship between the Propogation Speed and Surface Properties of Turbulent Premixed Flames

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Abstract - Lee This effort explores a possible dynamic relationship between the propagation speed and surface properties of turbulent premixed flames. Both flame surface properties and propagation speed are measured directly in fixed burner geometries. Recent findings of several researchers show that the rate of increase of the turbulent flame surface area is substantially lower than that for the observed flame speeds, casting doubt on Damkohler's assumption that the flame speed is proportional to the wrinkled flame surface area. This study addresses the source of this discrepancy and also gives fundamental insight into the mechanisms that cause the flame speed to increase as flame surface properties change with increasing turbulence. Two burner geometries are used: a pulsed-flame flow reactor that produces a freely propagating turbulent premixed flame, and a coaxial jet flame burner that stabilizes highly-turbulent premixed flames. Diagnostics include high-speed photography, conditional laser Doppler velocimetry for flame speed measurements, and two- and three-dimensional imaging for flame surface properties.