Calibration of Some Subsonic Wind Tunnel Inserts for Two-Dimensional Airfoil Experiments

Abstract : Parallel wall inserts were installed in the Naval Ship Research and Development Center 8 x 10-foot subsonic tunnel to create a 3 x 8 foot channel to serve as a high flow quality two-dimensional test section for high lift testing. A detailed flow survey indicated good flow uniformity, negligible angularity, a thin wall boundary layer at the model station, and a pronounced effect of trailing edge wall flaps on controlling test section dynamic pressure. A pair of two-dimensional airfoil sections tested in the facility displayed good agreement with reference data in lift and pressure distribution, but some disagreement in wake rake drag data. The strong influence of model lift on test section dynamic pressure measurement was noted, and a measurement technique was developed which was independent of the static pressure field propogating from the airfoil.