Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-27T13:16:23.593Z Has data issue: false hasContentIssue false

The laser-Doppler velocimeter and its application to the measurement of turbulence

Published online by Cambridge University Press:  29 March 2006

William K. George
Affiliation:
Applied Research Laboratory, The Pennsylvania State University
John L. Lumley
Affiliation:
Department of Aerospace Engineering, The Pennsylvania State University

Abstract

In 1964, Yeh & Cummins demonstrated that coherent light sources could be used for the measurement of steady fluid velocities by observing the Doppler shift in the frequency of light scattered from small particles moving with the fluid. Since 1964 many investigators have attempted to extend this technique to the measurement of turbulent velocity fluctuations.

A fundamental limitation on this type of velocimeter is the Doppler ambiguity introduced by the finite transit time of particles through the scattering volume, turbulent velocity fluctuations across the scattering volume, mean velocity gradients and electronic noise. A unified account of the effect of the Doppler ambiguity on the measurement of the instantaneous velocities is presented and results are interpreted using the power spectrum. The influence of the ambiguity on the measurement of other statistical quantities is also examined.

Limitations on the spatial and temporal resolution imposed by the finite sampling volume are examined using the power spectrum and criteria for optimization of the response are proposed.

An operational laser-Doppler velocimeter is described and measurements of spectra in both laminar and turbulent flow are presented. The experimental results are seen to be in excellent agreement with theoretical predictions.

Type
Research Article
Copyright
© 1973 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Batchelor, G. K. 1960 The Theory of Homogeneous Turbulence. Cambridge University Press.
Berman, N. S. & Dunning, J. W. 1973 J. Fluid Mech. to be published.
Clark, W. H. 1970 Measurement of two-point velocity correlations in a pipe flow using laser velocimeters. Ph.D. thesis, Department of Aerospace Engineering, University of Virginia, Charlottesville.
Clayton, W. 1954 Emulsions and Their Technical Treatment. London: Churchill.
Comte-Bellot, G. & Corrsin, S. 1966 The use of a contraction to improve the isotropy of grid-generated turbulence J. Fluid Mech. 25, 657682.Google Scholar
Davis, D. T. 1968 Analysis of a laser-Doppler velocimeter I.S.A. Trans. 7, 4351.Google Scholar
Edwards, R. V., Angus, J. C., French, M. J. & Dunning, J. W. 1971 Spectral analysis of the signal from the laser-Doppler velocimeter: time-independent systems. J. Appl. Phys. 42, 837850.Google Scholar
Foreman, J. W., Lewis, R. D. & Thornton, J. R. 1966 Laser-Doppler velocimeter for measurement of localized fluid velocities in liquids. Proc. I.E.E.E. 424.Google Scholar
George, W. K. 1971 An analysis of the laser-Doppler velocimeter and its application to the measurement of turbulence. Ph.D. thesis, Department of Mechanics, The Johns Hopkins University.
George, W. K. & Lumley, J. L. 1970 Limitations on the measurement of turbulence using a laser-Doppler velocimeter. Proc. Electro-Optical Conf., New York, p. 926.
George, W. K. & Lumley, J. L. 1971 The measurement of turbulence with a laser-Doppler velocimeter. A.S.C.E. Conf. Water Resources, Phoenix, no. 1345.Google Scholar
Goldstein, R. J. & Kreid, D. K. 1967 Turbulent flow measurements utilizing the Doppler shift of scattered laser radiation Phys. Fluids, 10, 1349.Google Scholar
Goodman, J. W. 1968 Introduction to Fourier Optics. McGraw-Hill.
Greated, C. A. 1969 Effect of polymer additives on grid turbulence. Nature, 224, 11961197.Google Scholar
Huffaker, R. M., Fuller, C. E. & Lawrence, T. R. 1969 Application of laser-Doppler velocity intrumentation to the measurement of jet turbulence. Int. Automotive Engng Congress, Detroit, Michigan.Google Scholar
Lading, L. 1970 Differential Doppler heterodyning technique. Appl. Optics, 10, 19431949.Google Scholar
Lawson, J. L. & Uhlenbeck, G. E. 1950 Threshold Signals. McGraw-Hill.
Lhermitte, R. M. 1968 Turbulent air motion as observed by Doppler radar. Proc. 13th RADAR Meteor. Conf., McGill University, Montreal.
Little, C. G. 1969 Acoustic methods for the remote probing of the lower atmosphere Proc. I.E.E.E. 57, 571578.Google Scholar
Lumley, J. L. 1961 The mathematical nature of the problem of relating Lagrangian and Eulerian statistical functions in turbulence. Mécanique de la Turbulence. Paris: C.N.R.S.
Lumley, J. L. 1970 Stochastic Tools in Turbulence. Academie.
Lumley, J. L., George, W. K. & Kobashi, Y. 1969 The influence of Doppler ambiguity and noise on the measurement of turbulent spectra using a laser-Doppler velocimeter. Proc. Symp. on Measurement of Turbulence in Liquids, University of Missouri at Rolla, p. 3.Google Scholar
Lumley, J. L. & Panofsky, H. A. 1964 The Structure of Atmospheric Turbulence. Interscience.
Mayo, W. T. 1969 Laser-Doppler flowmeter – a spectral analysis. Ph.D. thesis, Department of Electrical Engineering, Georgia Institute of Technology.
Mayo, W. T. 1970 Spatial filtering properties of the reference beam in an optical heterodyne receiver Appl. Optics, 9, 11591162.Google Scholar
Middleton, D. 1950 Spectrum of frequency-modulated waves Quart. Appl. Math. 8, 5981.Google Scholar
Pao, Y. H. 1965 Structure of turbulent velocity and scalar fields at large wavenumbers Phys. Fluids, 8, 1063.Google Scholar
Pike, E. R., Jackson, D. F., Bourke, P. J. & Page, D. I. 1967 Measurement of turbulent velocities from the Doppler shift in scattered laser light. Presentation at Div. Fluid Dyn., Am. Phys. Soc., Lehigh.Google Scholar
Rice, S. O. 1948 Statistical properties of a sine wave plus random noise. Bell Syst. Tech. J. 27, 109157.Google Scholar
Rice, S. O. 1954 Mathematical analysis of random noise. Selected Papers on Noise & Stochastic Processes (ed. N. Wax), p. 133. Dover.
Rolfe, E., Silke, J. K., Booth, S., Meister, K. & Young, R. M. 1968 Laser-Doppler velocity instrument. N.A.S.A. Current Rep. no. 1199.Google Scholar
Serrin, J. 1959 Mathematical principles of classical fluid mechanics. In Handbuch der Physik, vol. 8 (ed. S. Flugge), p. 1. Springer.
van de Hulst, H. C. 1957 Light Scattering by Small Particles. Wiley.
Welch, N. E. & Tomme, W. J. 1967 Analysis of turbulence from data obtained with a laser-Doppler velocimeter. A.I.A.A. Paper, no. 67–179.Google Scholar
Wiseman, W. J. 1969 On the structure of high frequency turbulence in a tidal estuary. Chesapeake Bay Inst., The Johns Hopkins University, Tech. Rep. no. 59.Google Scholar
Wyngaard, J. C. 1968 Measurement of small-scale turbulence structure with hot wires J. Sci. Instrum. 1, 1105.Google Scholar
Wyngaard, J. C. & Lumley, J. L. 1967 A sharp cutoff spectral differentiator J. Sci. Instrum. 44, 363365.Google Scholar
Yeh, H. & Cummins, H. Z. 1964 Localized fluid flow measurements with He-Ne laser spectrometer Appl. Phys. Lett. 4, 176.Google Scholar