Phased diode arrays for velocity measurements and signal processing

Dopheide, D.; Strunck, V.; Faber, M.

doi:10.1109/iciasf.1989.77654

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…One attempt at employing array diode lasers has been reported by Dopheide and Strunck [32]. The image of the periodic intensity distribution of the near field forms the fringe system in the measurement volume.…”

Section: Power Scalingmentioning

confidence: 99%

Laser Doppler velocimetry using powerful solid-state light sources

Czarske

2006

Meas. Sci. Technol.

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Opto-electronic measurement techniques are well established in fluid flow investigations. Their advantages are that they are non-intrusive, provide highly accurate measurement data and have fast response times. Laser Doppler velocimetry (LDV) is one of the most important methods for velocity measurements with high spatial and temporal resolution. Diode lasers and diode-pumped solid-state lasers as well as glass fibres and micro-optics are employed to an increasing extent. Particularly, the development of solid-state lasers proceeds rapidly. New lasers with improved properties such as high-power fundamental-mode emission make it possible to develop enhanced LDV sensor heads. This may open up new fields of application, for example in medicine and aerospace technology. The aim of this review is to describe the present state-of-the-art in LDV and to demonstrate how new laser concepts can still contribute to the development of new, improved LDV sensors. For that purpose, solid-state lasers such as diode lasers and diode-pumped solid-state lasers are introduced, and concepts of communication engineering for accomplishing directional multi-component velocity measurements are discussed. Also, velocity measurements with high spatial resolution are reported. A conclusive overview of applications and an outlook on future challenges are outlined.

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Section: Power Scalingmentioning

confidence: 99%

Laser Doppler velocimetry using powerful solid-state light sources

Czarske

2006

Meas. Sci. Technol.

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“…It is intended in future to determine the flow profiles not only in the inlet section but also inside the turbine gas meter using the LDA technique or laser-array velocimetry (LAV) [21]. This will allow more precise calculations of the thermodynamic properties to be made.…”

Section: I Work At the Lda Test Rigmentioning

confidence: 99%

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m³/h

1994

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In the Physikalisch-Technische Bundesanstalt (PTB) the primary standard for on-line flowrate measurements using the laser Doppler anemometer (LDA) technique has been extended to a three-component LDA to improve velocity profile measurements in the boundary layers of a nozzle flow. The LDA flowrate measuring facility now consists of a two-colour argon ion LDA and a wavelength-stabilized GaAlAs diode laser LDA. The gas flowrate is obtained by numerical integration of the measured velocity profiles across the exit plane of the nozzle. High local resolution of the velocity profile measurements is achieved by perpendicular orientation of the measurement volumes of the two-component gas laser LDA and the semiconductor diode laser LDA (LD-LDA). This allows the resolution in the boundary layer to be improved significantly to velocity gradients. The present work presents the LD-LDA system for precise velocity profile measurements at flow velocities of up to 120 m/s; selected profile measurements are described in detail to demonstrate the high resolution and the symmetry of the flow profile. For the first time a wavelength-stabilized miniaturized diode laser LDA has been successfully applied in precise velocity measurements, and comparisons with well-established gas laser LDAs have been made. The uncertainty of the flowrate measurement up to 5 500 m3/h is 0,l YO for air at atmospheric pressure. A turbine gas meter, type Elster G2500, was calibrated with the LDA and used as a transfer standard for an intercomparison with the Nederlands Meetinstituut (NMI) in the flowrate range up to 5 500 m3/h with and without the installation of perforated plates to condition the flow in the inlet section of the gas meter. The results of the comparison experiment clearly show the reliability and accuracy of the online flowrate measurement of gases and underline the necessity for a detailed research programme to investigate the relationship between installation effects, upstream flow conditions and the measurement uncertainty of gas meters. The design of a test rig now under construction at the PTB is shown. This will allow the diode laser LDA technique to be applied to the measurement of installation effects according to OIML Recommendation R-32.

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