Krypton Tagging Velocimetry for Use in High-Speed Ground-Test Facilities

Abstract

In this work, we present the excitation strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV) as applied to an underexpanded jet of three mixtures. We demonstrate that the KTV technique can be employed with gas mixtures of relatively low krypton concentration (0.5% Kr/99.5% N2) and conclude that the KTV technique shows promise as a velocimetry diagnostic with krypton as an inert, dilute, long-lifetime tracer in gas-phase flows. Nomenclature ∆x Distance traversed by metastable Kr, (m) ∆t Time between the write and read laser Q-switch pulses, (s) V Velocity, (m/s) D Diameter, (m) M Mach number, (-)

Krypton Tagging Velocimetry (KTV) Investigation of Shock-Wave/Turbulent Boundary-Layer Interaction

“…Balla and Everheart. 75 KTV was first demonstrated by Parziale et al 76,77 to measure the velocity along the center-line of an underexpanded jet of N 2 /Kr mixtures. In that work, pulsed-tunable lasers were used to induce fluorescence of Kr atoms that were seeded into the flow for the purposes of displacement tracking.…”

Nonintrusive Freestream Velocity Measurement in a Large-Scale Hypersonic Wind Tunnel

“…Using metastable noble gas as a tagging velocimetry tracer was first suggested by Mills et al [22] and Balla and Everheart [23]. KTV was first demonstrated by Parziale et al [24,25] to measure the velocity along the centerline of an underexpanded jet of N 2 ∕Kr mixtures. Following that work, Zahradka et al [26,27] used KTV to make measurements of the mean and fluctuating profiles in a Mach 2.7, 99% N 2 ∕1% Kr turbulent boundary layer.…”

“…This process takes approximately 50 ns [29] and comprises the "read line". We choose a different energy level for the read step as opposed to previous KTV work [24][25][26][27][28] because of higher observed signal-tonoise ratio (SNR) when performing the write/read steps in a stationary krypton cell. A fluorescence model that characterizes the SNR of the KTV technique with different read excitations is forthcoming and not included in this note.…”

Krypton Tagging Velocimetry in the Stevens Shock Tube

“…The use of a metastable noble gas as a tagging velocimetry tracer was first suggested by Mills et al 43 and Balla and Everheart. 44 KTV was first demonstrated by Parziale et al 45,46 to measure the velocity along the center-line of an underexpanded jet of N 2 /Kr mixtures. In that work, pulsed tunable lasers were used to induce fluorescence of Kr atoms that were seeded into the flow for the purposes of displacement tracking.…”