Fundamental studies of cavity-based flameholder concepts for supersonic combustors

Experimental and computational investigations of the flowfield associated with several cavity-based flameholders in a nonreacting supersonic how are described. All cavity flows were of the open type, that is, length-to-depth ratio L/D < 10, Two values of LID were studied with several offset ratios (OR) and aft ramp angles <theta>, Results indicate that the aft ramp angle plays an important role in determining the character of the shear layer that spans the cavity. For a rectangular cavity with OR = 1 and theta = 90 deg, a compression wave forms as the how separates from the cavity's upstream corner, A strong recompression occurs at the aft wall, and the how is visibly unsteady. The pressure on the cavity fore wall decreases steadily and the recompression process occurs more gradually with decreasing aft ramp angle, Higher drag coefficients and shorter residence times are found in cavities with shallower ramp angles.