Stereoscopic Particle Image Velocimetry Applied to Liquid Flows,

A twin-camera stereoscopic system has been developed to extend conventional high image-density. Particle Image Velocimetry PIV to three-dimensional vectors on planar do mains. The stereoscopic velocimeter performs with extremely high accuracy. Translation tests have yielded errors mu of 0.2 of full-scale for the in-plane displacement, and 0.8 of full-scale for the out-of-place component both of which agree with the errors predicted by an uncertainty analysis. In addition, modified techniques in hardware and software have enabled the stereoscopic system to perform successfully when acquiring images through a thick liquid layer, wherein previously the aberrations airing due to the liquid-air interface have restricted the use of such systems. With these techniques, the stereoscopic system, in combination with a simple method for image-shifting, is able to accurately measure three-dimensional velocity fields in liquids. This is demonstrated by measurement of the helical, three-dimensional flow induced by a rotating disk in glycerine. Author