Planar Doppler velocimetry: Three-component velocimetry in supersonic jets

A three-component planar Doppler velocimetry system was developed and used to make mean and instantaneous velocity measurements in a Mach 2 axisymmetr ic freejet. The mean measurements were in good agreement with reference las er Doppler velocimetry measurements taken in the same flowfield, whereas th e instantaneous measurements were in fair agreement and indicated areas tha t required improvement. A detailed uncertainty analysis provided further in sight into the performance of the planar Doppler velocimetry system. The ca libration of the splitter/recombiner imaging system using flatfield images was improved. Speckle image noise was found to be the largest source of err or affecting the turbulence results, and so digital filtering techniques we re investigated and employed.