20  kHz CH₂O and OH PLIF with stereo PIV

Abstract

Planar laser-induced fluorescence (PLIF) of hydroxyl (OH) and formaldehyde (CHO) radicals was performed alongside stereo particle image velocimetry (PIV) at a 20 kHz repetition rate in a highly turbulent Bunsen flame. A dual-pulse burst-mode laser generated envelopes of 532 nm pulse pairs for PIV as well as a pair of 355 nm pulses, the first of which was used for CHO PLIF. A diode-pumped solid-state Nd:YAG/dye laser system produced the excitation beam for the OH PLIF. The combined diagnostics produced simultaneous, temporally resolved two-dimensional fields of OH and CHO and two-dimensional, three-component velocity fields, facilitating the observation of the interaction of fluid dynamics with flame fronts and preheat layers. The high-fidelity data acquired surpass the previous state of the art and demonstrate dual-pulse burst-mode laser technology with the ability to provide pulse pairs at both 532 and 355 nm with sufficient energy for scattering and fluorescence measurement at 20 kHz.

Assessment of the stabilization mechanisms of turbulent lifted jet flames at elevated pressure using combined 2-D diagnostics

“…Attempts were also made to replace silicon oil with titanium dioxide particles but those were found to fluoresce in the visible range under excitation at 355 nm, which makes combining PIV with CH2O-PLIF very challenging [41]. Alumina particles have been shown by others to perform better [42,43] but those were not available at the time of the experiments.…”

High-speed two-color scanning volumetric laser-induced fluorescence

“…The development of the digital camera resulted in experimental two-dimensional imaging techniques such as planar laser-induced fluorescence (PLIF), particle imaging velocimetry (PIV), and particle tracking velocimetry (PTV). PLIF works by shining a laser sheet through a fluid sample that is embedded with a fluorescent tracer (Hammack et al (2018); Zhu et al (2019)). The fluorescent signal that arises from the laser sheet exciting the tracer is then captured by a camera.…”

Measurement of swirling flow in a blood chamber by laser Doppler imaging system

“…With this method, the two velocity components on the laser light plane, but not the perpendicular velocity component, are measured. Stereo PIV can also measure the perpendicular component using multiple high-speed video cameras and a thick laser light sheet [5,6], making it suitable [7] for measuring swirling flow in a tube. A method that uses an experimental device to record the transverse plane of a tube has been developed [4].…”