Three-component phase-averaged velocity measurements of an optically perturbed supersonic jet using multi-component planar Doppler velocimetry

In the planar Doppler velocimetry (PDV) technique, a molecular/atomic filte r is employed to convert frequency shifts in scattered light to intensity v ariations. The potential for instantaneous three-component velocity measure ments over an entire laser sheet makes PDV attractive for use in large wind tunnels. The development and integration of hardware and software for depl oyment of a multi-component PDV system is reported. Hardware issues address ed include observation of the long-term stability of a starved iodine cell. In addition, the accuracy of the dot-locating scheme, essential in the PDV data-reduction process, is investigated using numerically generated images . Finally, operation of a two-component system is demonstrated with velocit y measurements in a supersonic jet with a large-scale perturbation. Here, e nergy from a Nd:YAG laser is focused into the shear layer near the lip of t he nozzle to create a small thermal spot. The PDV technique is then employe d to study the evolution of the large-scale disturbance. Two orientations o f the two-component velocity measurement system are used to produce phase-a veraged three-component mean velocity measurements of the perturbed jet 170 and 220 mus after the introduction of the disturbance.