Abstract

Femtosecond laser electronic excitation tagging (FLEET) velocimetry is an important diagnostic technique for seedless velocimetry measurements particularly in supersonic and hypersonic flows. Typical FLEET measurements feature a single laser line and camera system to achieve one-component velocimetry along a line, although some multiple-spot and multiple-component configurations have been demonstrated. In this work, tomographic imaging is used to track the three-dimensional location of many FLEET spots. A quadscope is used to combine four unique views onto a single high-speed image intensifier and camera. Tomographic reconstructions of the FLEET emission are analyzed for three-component velocimetry from multiple FLEET spots. Glass wedges are used to create many (nine) closely spaced FLEET spots with less than 10% transmission losses. These developments lead to a significant improvement in the dimensionality and spatial coverage of a FLEET instrument with some increases in experimental complexity and data processing. Multiple-point three-component FLEET velocimetry is demonstrated in an underexpanded jet.

Dotted-line FLEET for two-component velocimetry

Yibin Zhang, Daniel Richardson, Garrett Marshall, Steven J. Beresh, and Katya M. Casper
Opt. Lett. 47(1) 98-101 (2022)

Multi-line FLEET by imaging periodic masks

Yibin Zhang, Garrett Marshall, Steven J. Beresh, Daniel Richardson, and Katya M. Casper
Opt. Lett. 45(14) 3949-3952 (2020)

Multi-point FLEET velocimetry in a Mach 4 Ludwieg tube using a diffractive optical element

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Appl. Opt. 63(4) 1087-1093 (2024)

Long-lived nitric oxide molecular tagging velocimetry with 1 + 1 REMPI

Naibo Jiang, Paul S. Hsu, Sukesh Roy, Jincheng Wang, Hui Hu, Neil Rodrigues, and Paul M. Danehy
Opt. Lett. 49(5) 1297-1300 (2024)

Burst-mode velocimetry of hypersonic flow by nitric oxide ionization induced flow tagging and imaging

Boris S. Leonov, Ashley N. Moran, Simon W. North, and Richard B. Miles
Opt. Lett. 49(3) 426-429 (2024)