Examination of the flow near the leading edge of attached cavitation. Part1. Detachment of two-dimensional and axisymmetric cavities

The flow near the cavity detachment region of stable attached cavitation wa s examined using qualitative and quantitative flow visualization. The non-c avitating and cavitating hows around a hydrophilic brass and hydrophobic Te flon sphere and cylinder were examined. The location of non-cavitating boun dary layer separation and cavity detachment was related to the free-stream Reynolds and cavitation numbers. The shape of the cavity near the detachmen t was greatly affected by the material of the cavitating object. The cavity interface on the hydrophilic test objects curved downstream to form a forw ard facing step. A region of recirculating fluid existed upstream of the ca vity interface. The cavity detachment on the hydrophobic test objects was m uch closer to the location of boundary layer separation. The forward facing step and the recirculating region were nearly absent. The measured how field near the surface of the brass sphere, cylinder, and hydrofoils under cavitating and non-cavitating conditions was used to calcu late the position of two-dimensional laminar boundary layer separation. Thw aites' and Stratford's methods were used to predict the location of boundar y layer separation upstream of the cavity detachment. The predictions compa red well with the observed position of separation.