Single camera three component planar velocity measurements using two-frequency planar Doppler velocimetry (2ν-PDV)

Two-frequency planar Doppler velocimetry (2 nu-PDV) is used in conjunction with imaging fibre bundles to make time-averaged three component velocity measurements using a single CCD camera and iodine cell. In this scheme the flow is sequentially illuminated with two different frequencies of laser light, which are separated by approximately 700 MHz to 1 GHz. Images are captured for each illumination frequency on a CCD camera viewing through an iodine absorption filter. These images are then used to produce a normalized transmission image that can be processed as in normal PDV. Three component measurements are made possible by porting separate views to a single CCD camera using the imaging fibre bundles. Results are presented here for a 2 nu-PDV system demonstrated making time-averaged velocity measurements on a rotating disc and a seeded air jet.