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 axisymmetric freejet. The mean measurements were in good agreement with reference laser Doppler velocimetry measurements taken in the same flowfield, whereas the instantaneous measurements were in fair agreement and indicated areas that required improvement. A detailed uncertainty analysis provided further insight into the performance of the planar Doppler velocimetry system. The calibration of the splitter/recombiner imaging system using flatfield images was improved. Speckle image noise was found to be the largest source of error affecting the turbulence results, and so digital filtering techniques were investigated and employed.