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We present a demonstration of the simultaneous measurement of spatially resolved three-component velocity and temperature in gaseous flow fields using a variant of the vibrationally excited nitric oxide monitoring (VENOM) technique, based on planar laser induced fluorescence and molecular tagging velocimetry methods. Three-component velocity determinations were derived from two-dimensional molecular tagging velocity measurements employing sequential fluorescence image pairs obtained simultaneously by two cameras in stereoscopic configuration. Probing two different rotational states of nitric oxide (Xsup2/sup∏, υsup''/sup=1), produced via fluorescence and collisional quenching from initial excitation to the A Σsup+/sup2 state, for the sequential velocimetry images allows simultaneous determination of the temperature field. Experimental measurements of velocity and temperature across an oblique shock result in mean values within 21 m/s for the three components of velocity and 20 K for planar temperature when compared to oblique shock calculations.

Laser Doppler velocimetry is used to measure very accurately the velocity and position of a microparticle propelled and guided by laser light in liquid-filled photonic crystal fiber. Periodic variations in particle velocity are observed that correlate closely with modal beating between the two lowest order guided fiber modes.

We report the development of a new method of instantaneously measuring three-dimensional velocity profiles and structure in air and oxygen. No seeding of particles, molecules, or atomic species is required. The method combines Raman excitation and laser-induced electronic fluorescence to generate a time-gated image of the moving oxygen molecules.

A method is reported for time- and space-resolved nonintrusive velocimetry of high-speed gas flows by measurement of the Doppler shift of light scattered from a laser-induced thermal grating. The principle is demonstrated by use of a pulsed frequency-doubled Nd:YAG laser to induce a thermal grating in NO(2) seeded into an argon flow. Signals are generated by Bragg scattering of probe beams at the fundamental frequency of the same Nd:YAG laser. Flow velocities in the range 30-180 ms(-1) are measured, in agreement with values obtained with a Pitot tube. The measurement uncertainties obtained indicate that a precision of 1% is feasible for flows at Mach 1.

A scheme for molecular tagging velocimetry is presented that can be usedin air f lows without any kind of seeding. The method is based on thelocal and instantaneous creation of nitric oxide (NO) molecules fromN2 and O2 in the waist region of a focused ArFexcimer laser beam. This NO distribution is advected by the flow and canbe visualized any time later by laser-induced fluorescence in the γ bands. The creation of NO is confirmed byuse of an excitation spectrum. Two examples of the application of thenew scheme for air-flow velocimetry are given in which single laserpulses are used for creation and visualization of NO.

A simultaneous two-dimensional determination of the concentration field and the velocity field in a turbulent mixing process is demonstrated for the first time to the best of our knowledge by using planar Raman scattering (Ramanography) and particle image velocimetry. An example of application of these techniques is tested by considering the mixing characteristic of a two-component nozzle for the injection of liquid ethanol into pure water.

We present measurements demonstrating simultaneous determination of velocity and temperature using a variant of the Vibrationally Excited Nitric Oxide Monitoring (VENOM) technique that does not employ NO2. The variant is based on tagging by electronic excitation of NO in the A2Σ1/2+(v′=0)←X2Π1/2(v′′=0) band and subsequent formation of vibrationally excited NO(X2Π) by spontaneous emission and collisional quenching. Sequential planar laser-induced fluorescence imaging of the nascent NO(X2Π,v′′=1) was used to obtain spatially resolved average streamwise velocity and rotational/translational temperature. The temperature determination using this approach extends the applicability of the VENOM technique to low-density, high-speed flows, where slow thermalization of the tagged molecules represents a limiting factor.

Ozone tagging velocimetry is developed for unseeded velocity measurement of air flows. An ozone line is photochemically created by an ArF excimer laser. After a fixed time delay the ozone line is imaged with a KrF excimer laser sheet (248 nm) that photodissociates the ozone and produces vibrationally excited O(2). The O(2) is excited by the same 248-nm light through the Schumann-Runge band, B (3)Sigma(u)(-)(upsilon' =0, 2) ? X (3)Sigma(g)(-)(upsilon'' = 6, 7). An intensified CCD camera records the O(2) fluorescence from the initial and the final line positions to permit the velocity profile along the line to be determined.