The effect of nuclei on the attachment hysteresis in cavitating trailing vortices

The incidence hysteresis between the attachment and detachment angles of a trailing vortex cavity behind an elliptical hydrofoil is investigated for two nuclei populations in a cavitation tunnel. Deplete and dense population were realized through natural and artificially seeded nuclei, respectively. The cavitation appearance was monitored for a range of incidences, and two hysteretic behaviours were observed. In a nuclei-deplete flow, the temporal delay equired to ingest and activate a susceptible nucleus and associated additional tension caused a larger incidence for cavity attachment. With dense seeding, however, the continual supply of nuclei into the cavity sustained the attached cavity at much lower incidences.