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Published August 2021 | public
Book Section - Chapter

Characterization of the Caltech Hypervelocity Expansion Tube via Tunable Diode Laser Absorption Spectroscopy


We report on measurements of freestream velocity in the Caltech Hypervelocity Expansion Tube (HET) facility. A novel diagnostic was developed based on velocimetry with Tunable Diode Laser Absorption Spectroscopy (TDLAS) targeting the D1 line of nascent atomic potassium. Two experiments at the same nominal condition showed steady flow velocity during the test time and strong agreement between experiments, but a higher velocity than expected from 1D inviscid calculations and preliminary viscous simulations. The goal of these experiments is the characterization of freestream flow conditions in the HET. Future efforts will perform this velocity characterization at additional facility conditions, measure freestream gas state properties, and reduce the measurement uncertainty due to beam alignment.

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© 2021 by the American Institute of Aeronautics and Astronautics, Inc.

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August 20, 2023
October 20, 2023