Improved alignment technique enabling cross-coupled operation of a 3D LDA for small-scale flow surveys

J. Rickards; C. Swales; C. J. Brake; R. V. Barrett

doi:10.1117/12.150570

6 August 1993 Improved alignment technique enabling cross-coupled operation of a 3D LDA for small-scale flow surveys

J. Rickards, C. Swales, C. J. Brake, R. V. Barrett

Proceedings Volume 2052, Fifth International Conference on Laser Anemometry: Advances and Applications; (1993) https://doi.org/10.1117/12.150570
Event: Laser Anemometry: Advances and Applications: Fifth International Conference, 1993, Koningshof, Veldhoven, Netherlands

Abstract

The paper describes a new alignment technique for three-dimensional Laser Doppler Anemometers (LDAs), which has enabled accurate velocity measurements to be obtained within very small flow regions. This technique uses a quantitative, rather than the more usual qualitative approach, to give greater consistency and reliability, resulting in greatly improved alignment of the laser beams. This enables much higher data rates and validity to be achieved, even in the critical cross-coupled mode, which in turn allows a significantly smaller measurement volume, thereby increasing the spatial resolution of the system. Examples are given which illustrate the type of small scale velocity surveys now possible as a result of this technique. These show 3D velocity surveys taken within the wake behind a 0.8 mm diameter surface particle in a boundary layer, and examples of three-component boundary layer velocity profiles in the order of 0.2 mm thick, recorded on a horizontally mounted cylinder rotating about a central vertical axis.

Citation Download Citation

J. Rickards, C. Swales, C. J. Brake, and R. V. Barrett "Improved alignment technique enabling cross-coupled operation of a 3D LDA for small-scale flow surveys", Proc. SPIE 2052, Fifth International Conference on Laser Anemometry: Advances and Applications, (6 August 1993); https://doi.org/10.1117/12.150570

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