Journal ArticleDOI
The performance of acousto-optic cells for laser-Doppler anemometry
Diamantino Durão,J. H. Whitelaw +1 more
Reads0
Chats0
TLDR
In this article, the performance of water filled acousto-optic cells is quantified with particular reference to their use for laser-Doppler anemometry, and the influence of the incident angle and the performance at frequencies close to but different from the fundamental frequency are quantified.Abstract:
The performance of water filled acousto-optic cells is quantified with particular reference to their use for laser-Doppler anemometry. With the cell operating at a frequency of 9.2 MHz, the intensities of the +1 and -1 order beams are shown to account for 76% of the transmitted light intensity for an electrical power input of 0.56W. The influence of the incident angle and the performance of a cell at frequencies close to but different from the fundamental frequency are quantified. Operation of the cells at a frequency of 30 MHz, i.e. close to a third harmonic, is shown to require significantly greater electrical power input but can without introducing thermal connection effects, allow the transmission of a first and zero order beams with equal intensities and a total loss of 8% of the incident intensity. To show that an acousto-optic cell can be used as a beam splitter and frequency shifter, measurements of three components of velocity are reported in the region of recirculation immediately downstream of the centre disc of an annular jet.read more
Citations
More filters
Journal ArticleDOI
Velocity characteristics of the flow in the near wake of a disk
Diamantino Durão,J. H. Whitelaw +1 more
TL;DR: In this article, the authors measured the velocity characteristics of near-wake flows with a direction-sensitive laser-Doppler anemometer and found that the curvature of the annular jet increases with disk diameter and the ratios of the maximum positive and negative centreline velocities to the exit velocity increase with decreasing disk diameter.
Journal ArticleDOI
Laser anemometry for combustion research
S. A. Self,J. H. Whitelaw +1 more
TL;DR: The state of the art of laser anemometry in the context of turbulent reacting flows is reviewed in this paper, where the basic principles and practice of LAM are discussed, and the relative merits of diff...
Journal ArticleDOI
Relationship between velocity and signal quality in laser Doppler anemometry
Diamantino Durão,J. H. Whitelaw +1 more
TL;DR: In this paper, the influence of particle velocity on the amplitude and visibility of the signal at the output from the photomultipliers was demonstrated and physical arguments to explain the measured results and to permit their interpolation and extrapolation.
Journal ArticleDOI
The application of quadrature demodulation techniques for the investigation of flows
TL;DR: Quadrature demodulation is presented as a promising LDA-signal processing technique for the evaluation of pedestal free quadrature burst signal pairs in the base band with high temporal resolution.
Journal ArticleDOI
Combustion-driven oscillations in a small tube
TL;DR: In this paper, the mean axial velocity and the rms of the corresponding fluctuations have been obtained by laser-Doppler anemometry for a range of operating conditions resulting in flames with and without discrete-frequency oscillations.
References
More filters
Journal ArticleDOI
Interaction between light and sound
TL;DR: In this article, a detailed discussion of a wide variety of applications, including signal processing devices, spectrum analyzers, television displays, image translators, memories, and the conversion of light into sound is presented.
Journal ArticleDOI
Two-Component, Self-Aligning Laser Vector Velocimeter
W. M. Farmer,J. O. Hornkohl +1 more
TL;DR: A newly developed laser Doppler velocimeter is described, which simplifies the optics usually required for the more conventional velocimeters, allows measurement of two-vector components of velocity, requires no adjustment of alignment mirrors, and enables both velocity component signals to be detected with a single detector.
Journal ArticleDOI
Pipe flow measurements of turbulence and ambiguity using laser-Doppler velocimetry
N. S. Berman,J. W. Dunning +1 more
TL;DR: In this paper, the ambiguities predicted by George and Lumley (1973) have been verified experimentally for turbulent pipe flows at Reynolds numbers from 5000 to 15,000 at the center line and near the wall.
Journal ArticleDOI
Efficient diffraction of light from acoustic waves in water
W. Kleinhans,D. L. Fried +1 more