Characterisation of vortices using pulsed-wave Doppler ultrasound

The detection and characterisation of vortices in a Kaman vortex generator by means of a pulsed-wave Doppler ultrasound system was assessed. Measurements were made at different steady flow rates in a 10 mm internal diameter tube, 14 mm distal to a circular cylinder of diameter 2 mm, placed across the tube inlet. The results were compared with those obtained with a two-component laser Doppler anemometer (LDA) system. There was generally good agreement between the two techniques in the measurement of frequency of vortex shedding and the circulation velocity of the vortices. We conclude that pulsed-wave Doppler ultrasound is a suitable technique for investigating vortical flow structures.