High-Speed Multi-Line OH Planar Laser-Induced Fluorescence in Unsteady Flames

Abstract

We describe the further development and application of a dual-injection-seeded optical parametric oscillator and associated kHz-rate burst-mode pump laser for high-speed OH planar laser-induced fluorescence in unsteady flames. A detailed overview of the novel double-pulse configuration of the burst-mode laser is given, indicating the potential for use in systems where both high energy and high repetition rate are necessary. Dual-wavelength injection-seeded operation of the optical parametric oscillator is demonstrated and preliminary OH PLIF line switching in a well-characterized natural-gas/air laminar diffusion flame is presented. Applications to high-speed nearly-instantaneous background capture for the elimination of laser scatter and background contamination from polycyclic aromatic hydrocarbons in fuel-rich hydrocarbon flames are also discussed and preliminary data are shown. Lastly, the potential for high-speed two-line planar OH thermometry is described including advantages of utilizing the burst-mode laser and multi-wavelength OPO for simplifying high-speed experimental systems.