Holographic particle image velocimetry system for measurements of hairpin vortices in air channel flow
Abstract
A holographic particle image velocimetry system for investigating hairpin vortices, artificially generated in a subcritical plane Poiseuille air flow, is presented. The optical setup is a modified version of the hybrid scheme, previously employed in turbulent water flows. Accordingly, separate reconstruction of holograms, successively recorded on the same photoplate, is provided by using two reference beams. The positioning of the photoplate within the image of the sample volume accompanied by special alignment procedures, minimizes the apparent displacement caused by the misalignment of the reconstruction waves. A novel method is employed for detecting in-focus particles. Testing the system with a fixed 5 μm diameter wire, results in a corresponding 3D wire image having a diameter of ≈25 μm. Finally, the instantaneous topology and 3D distribution of the two velocity components associated with the hairpin vortex are presented.
- Publication:
-
Experiments in Fluids
- Pub Date:
- May 2006
- DOI:
- 10.1007/s00348-006-0108-y
- Bibcode:
- 2006ExFl...40..708S