1 Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows (Invited)

This paper reviews five laser-induced fluorescence-based velocimetry techniques that have been used to study high-speed compressible flows at NASA Langley Research Center. The techniques discussed in this paper include nitric oxide (NO) molecular tagging velocimetry (MTV), nitrogen dioxide photodissociation (NO2-to-NO) MTV, and NO and atomic oxygen (O-atom) Doppler-shift-based velocimetry. Measurements of both single-component and two-component velocity have been performed using these techniques. This paper details the specific application and experiment for which each technique has been used, the facility in which the experiment was performed, the experimental setup, sample results, and a discussion of the lessons learned from each experiment. Nomenclature AoA = angle-of-attack c = speed of light, m/s CCD = charge coupled device CFD = computational fluid dynamics LIF = laser-induced fluorescence λ = wavelength, nm MTV = molecular tagging velocimetry NO = nitric oxide NO2 = nitrogen dioxide Pstatic = static pressure, Pa PLIF = planar laser-induced fluorescence PMT = photomultiplier tube SLPM = standard liters per minute SNR = signal-to-noise ratio Tstatic = static temperature, K tadd = additional delay, ns tE1 = first exposure duration, ns tE2 = second exposure duration, ns tGD = gate delay, ns tGW = intensifier gate width, n