Lewis number effects on premixed flames interacting with turbulent Karman vortex streets

Conference · Sun Jan 01 04:00:00 EST 1995 · Combustion and Flame; (United States)

OSTI ID:6799105

Lee, J G; Lee, T W; Nye, D A; Santavicca, D A ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States)

The effects of Lewis number on the global and local structure of premixed flames interacting with turbulent Karman vortex streets are experimentally investigated using OH planar-laser-induced fluorescence (PLIF). The OH PLIF results show that over the range of Lewis numbers studied, i.e., Le = 0.21, 0.94 and 1.79, the flame area increases and the flame front is oriented more randomly as Lewis number decreases, while the flame curvature pdfs are unchanged. The relationship between the local flame structure and the local flame curvature is found to be consistent with the results of stretched laminar flame theory. the correlation between the local maximum OH fluorescence intensity and the local curvature tends to level off for large positive curvature as U/S ratio increases, indicating that the response of the flame to large flame stretch may be non-linear at high U/S ratio. The pdfs of peak OH LIF intensity suggest that the mean burning rate of the H[sub 2]/He/air flame at U/S ratios = 3.3 is increased approximately by 10% in comparison to the undisturbed laminar flame. The present results imply that even though the local fame curvature may strongly influence the local structure and burning rate of nonunity Lewis number flames through the effect of flame stretch on the local burning rate, these variations tend to cancel in the mean due to the linear relationship between local burning rate and curvature for the most probable values of curvature and due to the symmetry and zero mean of the curvature distribution. Therefore, the main effect of turbulence and Lewis number is to wrinkle the flame and produce flame area, while increasing the mean burning rate per unit surface area by relatively small amount through flow strain effects.

• OSTI ID: 6799105
• Report Number(s): CONF-940711--
• Conference Information: Journal Name: Combustion and Flame; (United States) Journal Volume: 100:1-2
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
CURRENTS
ELEMENTS
FLAMES
FLUID FLOW
FLUID MECHANICS
FLUIDS
GAS FLOW
GASES
HELIUM
HYDROGEN
HYDROXYL RADICALS
KINETICS
MATHEMATICAL MODELS
MECHANICS
MORPHOLOGY
NONMETALS
RADICALS
RARE GASES
REACTION KINETICS
TURBULENT FLOW