An Experimental Investigation of Vortex Rings and Helicopter Rotor Wakes Using a Laser Doppler Velocimeter

Abstract

The report describes a laser Doppler velocimeter (LDV) capable of performing measurements in vortex cores, presents detailed measurements of structure and stability of vortex rings and also presents measurements in the wake of a model helicopter rotor. The use of conventional instrumentation such as hot wire anemometer for measuring velocity in vortex filament is hampered by probe interference and the difficulty of calibrating the probe in a flow field where the velocity is changing rapidly in magnitude and direction. For these reasons, a laser Doppler velocimeter (LDV) is used throughout these experiments. The LDV measures the velocity of smoke particles by measuring the Doppler shift of laser light scattered from the particles. (Modified author abstract)

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 1973
Accession Number
AD0778768

Entities

People

  • John P. Sullivan

Organizations

  • Massachusetts Institute of Technology

Tags

Communities of Interest

  • Advanced Electronics
  • Air Platforms

DTIC Thesaurus Topics

  • Coordinate Systems
  • Doppler Effect
  • Flow Fields
  • Flow Visualization
  • Fluid Flow
  • Frequency
  • Geometry
  • Hot Wire
  • Hot Wire Anemometers
  • Laser Beams
  • Measurement
  • Refractive Index
  • Scattering
  • Solid Bodies
  • Two Dimensional
  • Velocimeters
  • Waves

Fields of Study

  • Physics

Readers

  • Aerodynamics.
  • Fluid Dynamics.

Technology Areas

  • Directed Energy