Development of high-spectral-resolution planar laser-induced fluorescence imaging diagnostics for high-speed gas flow

We report measurements of pressure and temperature in an underexpanded jet using planar laser-induced fluorescence (PLIF) of nitric oxide (NO). Ultraviolet transitions near 44,097.5 cm-1 in the A-X (0,0) system of NO were excited using narrow linewidth laser radiation generated from an optical parametric system injection-seeded using a distributed feedback (DFB) diode laser. PLIF images with excellent spatial resolution and signal-to-noise ratio were acquired by tuning the temperature of the DFB laser over the NO absorption line. The images were corrected for shot-to-shot fluctuations in the laser spatial profile. Lineshapes constructed from the corrected PLIF images were used to obtain pressure and temperature values along the centerline of the jet. Excellent agreement between LIF and previously reported N2 CARS measurements was observed. The measurements compared well with predictions of pressure and temperature using computational fluid dynamics codes. The LIF technique can be potentially applied to obtain instantaneous measurements of thermodynamic properties and velocity in high-speed turbulent flows. Copyright 2008 by the American Institute of Aeronautics and Astronautics, Inc.

Development of high-spectral-resolution planar laser-induced fluorescence imaging diagnostics for high-speed gas flow Conference Paper