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Published May 2021 | public
Journal Article

Freestream velocity-profile measurement in a large-scale, high-enthalpy reflected-shock tunnel


We apply Krypton Tagging Velocimetry (KTV) to measure velocity profiles in the freestream of a large, national-scale high-enthalpy facility, the T5 Reflected-Shock Tunnel at Caltech. The KTV scheme utilizes two-photon excitation at 216.67 nm with a pulsed dye laser, followed by re-excitation at 769.45 nm with a continuous laser diode. Results from a nine-shot experimental campaign are presented where N₂ and air gas mixtures are doped with krypton, denoted as 99% N₂/1% Kr, and 75% N₂/20% O₂/5% Kr, respectively. Flow conditions were varied through much of the T5 parameter space (reservoir enthalpy h_R ≈ 5−16 MJ/kg). We compare our experimental freestream velocity-profile measurements to reacting, Navier–Stokes nozzle calculations with success, to within the uncertainty of the experiment. Then, we discuss some of the limitations of the present measurement technique, including quenching effects and flow luminosity; and, we present an uncertainty estimate in the freestream velocity computations that arise from the experimentally derived inputs to the code.

Additional Information

© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021. Received 30 December 2020; Revised 08 April 2021; Accepted 10 April 2021; Published 05 May 2021. We would like to acknowledge Prof. Hans Hornung of Caltech for providing valuable advice regarding all aspects of the project. Additionally, we would like to thank Bahram Valiferdowsi, also of Caltech, for operating the tunnel and assisting with the experimental setup. Mustafa and Parziale were supported by AFOSR Young Investigator Program Grant FA9550-16-1-0262 and AFOSR Grant FA9550-18-1-0403; equipment for this work was supported by AFOSR DURIP Grants FA9550-15-1-0325 and FA9550-19-1-0182. Support was provided by US Air Force Small Business Innovation Research grants FA9101-17-P-0094 and FA2487-19-C-0013. Shekhtman was supported by the Stevens Institute of Technology Provost Fellowship and the ONR Young Investigator Research Program Grant N00014-20-1-2549. Yu and Austin were partially supported by AFOSR Grant FA9550-19-1-0219. The authors declare that they have no conflict of interest.

Additional details

August 20, 2023
October 23, 2023