Dual Cylindrical Wave Laser-Doppler Method for Measurement of Skin Friction in Fluid Flow.

Abstract

The objective of the present work is to overcome the inadequacies of conventional skin friction measuring methods in terms of temporal and spatial resolution. An instrument has been developed for measurement of the instantaneous velocity gradient in a boundary layer at a solid surface, from which the instantaneous wall shear stress can be deduced. The principle of the device is akin to that of dual beam Laser Doppler Anemometer. Instead of crossing two laser beams to produce the measuring volume, the present technique uses interference between two closely spaced cylindrical waves emanating from the solid surface. The interference fringes which constitute the measuring volume appear to be radiating from a point on surface. Keywords: Skin friction; Fluid flow; Lasers; Boundary layers; Doppler method; Wall shear stress; Laser beams; Cylindrical waves.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1987
Accession Number
ADA178629

Entities

People

  • Amir A. Naqwi
  • William C. Reynolds

Organizations

  • Stanford University

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Acousto-Optic Modulators
  • Boundary Layer
  • Boundary Layer Flow
  • Computational Fluid Dynamics
  • Computational Science
  • Diffraction
  • Doppler Effect
  • Fluid Dynamics
  • Fluid Flow
  • Hydrodynamics
  • Laser Beams
  • Measurement
  • Optical Phenomena
  • Optical Properties
  • Optics
  • Turbulent Flow
  • Two Dimensional

Fields of Study

  • Physics

Readers

  • Electromagnetic Wave Scattering and Antenna Radiation Engineering
  • Fluid Dynamics.
  • Optical Physics and Photonics.

Technology Areas

  • Directed Energy
  • Space
  • Space - Hall-Effect Thruster