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

In the planar Doppler velocimetry (PDV) technique, a molecular/atomic filter is employed to convert frequency shifts in scattered light to intensity variations. The potential for instantaneous three-component velocity measurements over an entire laser sheet makes PDV attractive for use in large wind tunnels. The development and integration of hardware and software for deployment of a multi-component PDV system is reported. Hardware issues addresssed 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 velocity measurements in a supersonic jet with a large-scale perturbation. Here, energy from a Nd: YAG laser is focused into the shear layer near the lip of the nozzle to create a small thermal spot. The PDV technique is then employed to study the evolution of the large-scale disturbance. Two orientations of the two-component velocity measurement system are used to produce phase-averaged three-component mean velocity measurements of the perturbed jet 170 and 220 μs after the introduction of the disturbance.