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Proceedings Paper

Diode laser absorption tomography using data compression techniques
Author(s): Chad Lindstrom; Chung-Jen Tam; Ryan Givens; Doug Davis; Skip Williams
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Paper Abstract

Tunable diode laser absorption spectroscopy (TDLAS) shows promise for in situ monitoring in high-speed flows. However, the dynamic nature of typical flows of supersonic combustors, gas turbine engines and augmenters can also lead to inhomogenities that cannot be captured by a single line-of-sight TDLAS measurement. Instead, multiple measurements varied over several spatial locations need to be made. In the current study, shock train structure in the isolator section of the Research Cell 18 supersonic combustion facility at Wright-Patterson AFB is measured. Although only two view angles are available for measurement, multiple absorption features along with a priori computational fluid dynamics (CFD) simulations enable estimates of two dimensional flow features to be formed. Vector quantization/kmeans data clustering is used to identify key flow features from the temporal history of the raw sinograms. Through the use of multiple absorption features that are measured nearly simultaneously, an approximate two-dimensional image can be formed. This image can be further refined through the use of an optimal set of basis functions that can be derived from a set of CFD simulations that describes the flow shapes.

Paper Details

Date Published: 26 February 2008
PDF: 17 pages
Proc. SPIE 6814, Computational Imaging VI, 68140W (26 February 2008); doi: 10.1117/12.766323
Show Author Affiliations
Chad Lindstrom, Air Force Research Lab. (United States)
Chung-Jen Tam, Taitech, Inc. (United States)
Ryan Givens, Air Force Institute of Technology (United States)
Doug Davis, Air Force Research Lab. (United States)
Skip Williams, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 6814:
Computational Imaging VI
Charles A. Bouman; Eric L. Miller; Ilya Pollak, Editor(s)

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