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Abstract:

An experimental investigation was conducted to determine the effect of Reynolds number (separate from boundary layer thickness) and the effect of yaw angle on the pressure distribution in a rectangular-box cavity. The cavity (11.25 in. long and 2.5 in. wide) was tested over a Mach number range from 0.20 to 0.90, unit Reynolds numbers from 2 x 10(exp 6) to 100 x 10(exp 6) per foot and at yaw angles of 0 and 15 degrees. Cavities were tested with length-to-height ratios (l/h) of 4.4, 6.7, 12.67, and 20.0. Fluctuating and static pressure data are presented. The cavity model was mounted in the sidewall of the NASA, Langley 0.3-meter transonic cryogenic tunnel. The thickness of the sidewall boundary layer entering the cavity was measured with a Pitot pressure rake and the tabulated values are provided. For the range of Reynolds numbers tested, Reynolds numbers had no significant effect on the static pressure distributions. The effect of yaw on the cavity pressure distribution was most pronounced when the flowfield was of the open type at yaw = 0 degrees. In such cases, the flowfield became transitional when the cavity was positioned at yaw = 0 degrees. However, if the flowfield, at yaw = 0 degrees, was transitional or closed, the effect of 15 degree yaw on the pressure distribution was very minimal. The types of flow field observed for given ranges of cavity 1/h at supersonic conditions were shown to occur at different ranges of 1/h for subsonic and transonic conditions.

Author(s):
E.B. Plentovich; J. Chu; M.B. Tracy