100 kHz krypton-based flow tagging velocimetry in a high-speed flow
Abstract
Krypton (Kr)-based tagging velocimetry is demonstrated in a K r / N 2 jet at 100 kHz repetition rate using a custom-built burst-mode laser and optical parametric oscillator (OPO) system. At this repetition rate, the wavelength-tunable, narrow linewidth laser platform can generate up to 7 mJ/pulse at resonant Kr two-photon-excitation wavelengths. Following a comprehensive study, we have identified the 212.56 nm two-photon-excitation transition as ideal for efficient Kr-based velocimetry, producing a long-lived ( ∼ 40 µ s ) fluorescence signal from single-laser-pulse tagging that is readily amenable to velocity tracking without the need for a second “read” laser pulse. This long-lived fluorescence signal is found to emanate from N 2 —rather than from Kr—following efficient energy transfer. Successful flow velocity tracking is demonstrated at multiple locations in a high-speed K r / N 2 jet flow. The 100 kHz repetition rate provides the ability to perform time-resolved velocimetry measurements in high-speed and even hypersonic flow environments, where standard velocimetry approaches are insufficient to capture the relevant dynamics.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 16, 2021
- Source ID
- 10.1364/ao.415976
Entities
People
- Hans U. Stauffer
- Josef J. Felver
- Naibo Jiang
- Paul Hsu
- S. Alexander Schumaker
- Stephen W. Grib
- Sukesh Roy
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory