Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers

The use of Particle Image Velocimetry (PIV), which uses digital cameras for data acquisition) to study high speed fluid flows is usually limited by the camera frame acquisition rate. The velocity of the fluid under study must be limited to insure that particles suspended in the flow field remain in the camera's focal plane in successive images. However, the use of digital cameras for data acquisition is desirable to simplify and expedite the data analysis. A method is presented which will measure changes in the flow field which occur at the relatively fast framing rate of 100 to 320 s per frame. However, in order to achieve this framing rate the laser has to be operated in a double pulse mode with one camera exposed twice. The directional ambiguity presented by the double exposure can be resolved by capturing a single exposure of the second pulse with a second digital camera. The study of collapsing steam bubbles also presents the problem of distinguishing between the light reflected by the liquid-gas interface and the light refracted by the surrounding tracer particles. This problem was resolved through the use of fluorescent seeds and appropriate filters. The filter blocked most of the green light reflected by the bubbles and passed the red light emitted by the fluorescent seeds.

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED

Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers Conference Paper