Accession Number : AD0743530

Title :   Spectral Analysis of the Signal from the Laser Doppler Velocimeter. Turbulent Flows,

Corporate Author : CASE WESTERN RESERVE UNIV CLEVELAND OHIO CHEMICAL ENGINEERING DIV

Personal Author(s) : Edwards,Robert V. ; Angus,John C. ; Dunning,John W. , Jr

Report Date : 28 MAR 1972

Pagination or Media Count : 24

Abstract : The power spectrum of phototube current from a Laser Doppler Velocimeter operating in the heterodyne mode has been computed. The spectrum is obtained in terms of the space time correlation function, for turbulent flow of the fluid. The spectral width and shape predicted by the theory is in agreement with experiment. For normal operating parameters the time average spectrum contains information only for times shorter than the Lagrangian integral time scale of the turbulence. To examine the long time behavior one must use either extremely small scattering angles much longer wavelength radiation or a different mode of signal analysis, e.g., F.M. detection. (Author)

Descriptors :   (*FLOWMETERS, LASERS), POWER SPECTRA, FLOW FIELDS, SCATTERING, DOPPLER EFFECT, TURBULENCE

Subject Categories : Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE