Jet Reattachment to Walls of Various Shapes

Abstract

Velocity fields for jets reattaching to walls of various shapes (curved and inclined straight), setbacks, and control port conditions were examined experimentally for the case of undeveloped velocity profiles at the nozzle exit. A canting of the nozzle exit profile occurred for cases where the wall was set back from the lip of the nozzle exit. Significantly different growth characteristics were observed for the case of the inclined straight wall, relative to the curved walls, due to the sharp turning angle which the jet was required to negotiate in the vicinity of the nozzle exit. For each jet, a well-defined settling length was noted by plotting the position of the maximum velocity versus arc length from the nozzle exit. Whenever possible, results were compared with previous investigations for fully developed conditions at the nozzle exit. Off-midplane total pressure profiles were taken for the inclined straight wall and a curved wall at several arc lengths, and three-dimensional effects were found to be significant for arc lengths and nozzle aspect ratios of interest in digital flueric amplifiers.