1994 Volume 60 Issue 572 Pages 1133-1138
In order to clarify the mechanism of the severe erosion mainly resulting from the singular vortex cavitation, we carefully observe the vortex cavitation associated with the erosion around a butterfly valve by means of a high-speed video camera, whose framing rate is 40500 per second. The velocity of cavitating flow is measured by the digital-image processing technique. It is worth noting that the vortex cavitation develops in the boundary region between the main flow region, i. e., the orifice-jet, and the recirculating region. The cavitating vortex core consists of several tiny vortex cavitations. The rotating velocity of the highly erosive vortex cavitation can also be determined by this technique.