| To identify and understand the fluid dynamic processes associated with flow in the region of a flap side edge, a NACA 63-215 Mod B main element with a half-span Fowler flap was tested in the JIAA Low Speed Wind Tunnel at Stanford University. Measurements were made using a variety of techniques to capture the effects of the flap edge vortex. Pressure sensitive paint was applied to the upper surface of both the flap and main element, as well as to the flap side edge. Fast response pressure transducers were mounted interior to the model to measure surface pressure fluctuations on the flap side edge. Single component hotwire data was taken in the near wake region of the flap edge. In addition to the data experimentally obtained, a computational data set of a geometrically similar model at a flight Reynolds number was used for comparison. The data indicates the presence of a dual vortex structure along the flap side edge. This structure is seen to grow, merge, and ultimately become a single symmetric vortex as it progresses downstream. Surface pressure fluctuations on the side edge scale as three power laws with free stream velocity as different flow regions are encountered. By varying the model rigging, indications of a confined source region for the pressure fluctuations were observed. A spatial survey of the correlation between flap side edge surface pressure fluctuations and the near-wake fluctuating velocity field shows increased correlation coefficients for the region surrounding the vortex core. |
