Accession Number : ADA257045


Title :   NACA 0015 Wing Pressure and Trailing Vortex Measurements


Descriptive Note : Technical paper


Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER


Personal Author(s) : McAlister, K W ; Takahashi, R K


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a257045.pdf


Report Date : Nov 1991


Pagination or Media Count : 142


Abstract : A NACA 0015 semispan wing was placed in a low-speed wind tunnel, and measurements were made of the pressure on the upper and lower surface of the wing and of the velocity across the vortex trailing downstream from the tip of the wing. Pressure data were obtained for both 2D and 3D configurations. These data feature a detailed comparison between wing tips with square and round lateral edges. A two-component laser velocimeter was used to measure velocity profiles across the vortex at numerous stations behind the wing and for various combinations of conditions. These conditions include three aspect ratios, three chord lengths, a square- and a round-lateral tip, presence or absence of a boundary-layer trip, and three image plane positions located opposite the wing tip. Both pressure and velocity measurements were made for angles of attack of 4 deg less then or equal to alpha less then or equal to 12 deg and for Reynolds. numbers of 1 x 10 deg less then or equal to Re less then or equal to 3 x 10 deg. The addition of a round-lateral edge to the wing Up was found to eliminate the secondary vortex near the wing Up, but had little effect on the downs characteristics of the trailing vortex. The increase in wing lift near the Lip because of the presence of the trailing vortex was evident in the surface pressure, but was not captured by circulation-box measurements. The circumferential velocity within the vortex was found to reach free-stream values and produce core rotational speeds as high as 44,000 rpm. The streamwise velocity within the viscous wake that is shed from the wing was observed to form islands of peak velocity in the spiraling sheet that feeds into the trailing vortex.


Descriptors :   *TRAILING VORTICES , *PRESSURE , *WINGS , VELOCITY , STATIONS , ANGLES , MEASUREMENT , RATIOS , CORES , BOXES , SURFACES , FREE STREAM , LIFT , NUMBERS , VALUE , WAKE , SHEETS , IMAGES , CONFIGURATIONS , PROFILES , BOUNDARY LAYER TRIPS , ADDITION , LASER VELOCIMETERS , ISLANDS , ASPECT RATIO , WIND TUNNELS , CIRCULATION , REGIONS , LASERS , LAYERS , EDGES , SECONDARY , COMPARISON , ATTACK


Subject Categories : Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE