Accession Number : ADP008953

Title :   LDA Measurements of the Unsteady Near Wake Behind an Airfoil Undergoing Transient and Periodic Pitching Motions,

Corporate Author : TECHNICAL UNIV OF LISBON (PORTUGAL)

Personal Author(s) : Wernert, P. ; Koerber, G. ; Wietrich, F.

Report Date : 23 JUL 1992

Pagination or Media Count : 6

Abstract : This paper presents results of two-dimensional LDA measurements performed in the near wake of an airfoil undergoing stepwise motions and saw-tooth periodic motions with incidence variations from -1 deg to 25 deg, revealing dynamic stall features. The driving mechanism used here is a new one, based on an automatic apparatus, which allows the airfoil to be put into a wide range of periodic or transient pitching and/or heaving motions. Time-dependent velocity traces for the two components, streamwise velocity profiles, evolution of the semi wake thickness and vector velocity field are discussed. These results, obtained at a Reynolds number of 267000, are compared to those corresponding to steady flow. (Author)

Descriptors :   *LASER ANEMOMETERS, *UNSTEADY FLOW, *WAKE, TRAILING EDGES, PITCH(MOTION), AIRFOILS, DOPPLER EFFECT, TWO DIMENSIONAL FLOW, STALLING, REYNOLDS NUMBER, WIND TUNNEL TESTS, ANGLE OF ATTACK, FRANCE.

Subject Categories : Fluid Mechanics
      Optical Detection and Detectors
      Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE