Flame Structure of Vitiated Fuel-Rich Inverse Diffusion Flames in a Cross-Flow (Postprint)
Conference paper (postprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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Fuel-rich streaks or dissociated combustion products exiting from gas turbine combustors may react with jets of turbine vane cooling air. These fuel-rich vitiated inverse diffusion flames can potentially cause structural failure of turbine vanes due to the excessive heat fluxes. In this study OH planar laser induced fluorescence measurements are conducted in fuel-rich vitiated flows advecting over a flat plate with a row of cooling holes normal to the surface. Vitiated conditions are generated by burning propane at equivalence ratios between 1.1 and 1.4 in a well-stirred reactor located upstream of the test section. The structures of the flames i.e., spatially-resolved species measurements are compared for different equivalence ratios and blowing ratios. It is observed that the flames generated by the cooling air are inherently unsteady, with the standard deviation of the flame tip location varying by as much as 35. The distance downstream of the slot where the flame tip was observed varies by 20 or less with respect to the average for a factor of 20 increase in the blowing ratio. The separation between the flame and the wall is similar for blowing ratios between 1 and 5, but increases for a blowing ratio of 10. Changing the equivalence ratio of the vitiated flow has little effect on the location where flames are observed.
- Combustion and Ignition