OH Planar Laser-Induced Fluorescence Velocity Measurements in a Supersonic Combustor

Abstract

Quantitative velocity measurements have been made in a hydrogenlair reacting flow in a supersonic combustor model. These measurements were made with an unswept ramp fuel injector in a clean-air, electrically heated supersonic combustion tunnel. A nonintrusive optical velocity measurement technique based on OH planar laser-induced fluorescence (OH PLIF) has been used for this study. A narrow line-width, tunable, pulse-amplified, doubled-dye uv beam was used to resolve an OH spectral line by monitoring the laser-induced fluorescence at every point in the measurement plane. The Doppler-shifted line center was measured with a counterpropagating scheme to eliminate collisional impact shifts. Velocity fields were measured in five planes parallel to the injector wall. The maximum streamwise component is 700-800 m/s and the transverse spreading component is much smaller compared to the streamwise component. These measurements have an uncertainty of ±6-8% in flow regions with the maximum velocity. The spatial resolution and accuracy of these measurements provide a unique benchmark data set (which also includes OH PLIF absolute concentration and temperature) for computational fluid dynamics validation of reacting supersonic combustion flows.