Microbubble disperse flow about a lifting surface

The effect of freestream nuclei content on stablecavitation about a hydrofoil and subsequent microbubbleproduction in the wake is investigated experimentally. Microbubble concentrations are measured upstream anddownstream of the hydrofoil for four upstream nucleiconcentrations and three cavitation numbers. For eachcase the number of activated nuclei on the hydrofoiland the transverse distribution of concentrations in thewake were measured. Upstream nuclei concentrationswere measured with interferometric Mie imaging in thesize range between 45-250 µm at concentrations upto 30 cm−3. Wake microbubble concentrations weremeasured using shadowgraphy in the size range 5-50 µmat concentrations up to 600 cm−3. Wake concentrationwere found to increase for small changes in low upstreamnuclei concentrations but to then decrease for furtherincrease in concentrations. Wake concentrations werefound to generally increase with decrease in cavitationnumber for a particular upstream nuclei concentration.The increase in wake bubble concentrations with seedingincrease, at the high cavitation number, is in the smallerbubble size range whereas the increase at the lowercavitation numbers occurs over a greater size range