Accession Number : ADA300329

Title :   3-D Wake Measurements Near a Hovering Rotor for Determining Profile and Induced Drag.

Descriptive Note : Technical paper,

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

Personal Author(s) : McAlister, K. W. ; Schuler, C. A. ; Branum, L. ; Wu, J. C.

PDF Url : ADA300329

Report Date : AUG 1995

Pagination or Media Count : 70

Abstract : Primarily an experimental effort, this study focuses on the velocity and vorticity fields in the near wake of a hovering roton Drag terminology is reviewed, and the theory for separately determining the profile- and induced-drag components from wake quantities is introduced. Instantaneous visualizations of the flow field are used to center the laser velocimeter (LV) measurements on the vortex core and to assess the extent of the positional meandering of the trailing vortex. Velocity profiles obtained at different rotor speeds and distances behind the rotor blade clearly indicate the position, size, and rate of movement of the wake sheet and the core of the trailing vortex. The results also show the distribution of vorticity along the wake sheet and within the trailing vortex.

Descriptors :   *TRAILING VORTICES, *WAKE, *AERODYNAMIC DRAG, VELOCITY, MATHEMATICAL MODELS, COMPUTATIONAL FLUID DYNAMICS, HELICOPTER ROTORS, ROTOR BLADES(ROTARY WINGS), FLOW VISUALIZATION, VORTEX SHEDDING, PRESSURE MEASUREMENT, FLOW FIELDS, PROFILES, AERODYNAMIC LOADING, FREE STREAM, THRUST, PRESSURE DISTRIBUTION, TORQUE, SKIN FRICTION, HOVERING, LASER VELOCIMETERS, THREE DIMENSIONAL FLOW, BLADE TIPS.

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE