Accession Number:

AD0766828

Title:

The Stability of Helical Vortex Filaments in the Wake of a Hovering Rotor,

Descriptive Note:

Corporate Author:

WEST VIRGINIA UNIV MORGANTOWN DEPT OF AEROSPACE ENGINEERING

Personal Author(s):

Report Date:

1973-05-01

Pagination or Media Count:

141.0

Abstract:

An experimental investigation was performed to study the geometry and stability of the wake of a hovering rotor out of ground effect. A schlieren system in conjunction with a high speed drum camera was developed for this purpose, so that real-time sequence photographs could be taken of the vortex filaments as they were convected downstream. Two, three, and four bladed 16-inch diameter rotors were used operating at rotor speeds of up to 9000 RPM. The effects of a rotor speed, number of blades, and collective pitch, were correlated with the stability of the vortex wake system. Four modes of vortex filament instabilities were observed. Other topics discussed are the effect of rotor blade mismatching upon the performance of the rotor and the effect of rotor blade tip modifications upon the trailing vortex formation and performance of the rotor system. Blade tips of elliptical, square and ogee designs were investigated. Schlieren pictures are included from both studies. Modified author abstract

Subject Categories:

  • Aerodynamics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE