A third procedure for linearized fully cavitating hydrofoil section design

The third design procedure for fully cavitating hydrofoils is based upon a linearized inverse theory of two-dimensional capacity flows at arbitrary cavitation number. The cavity surfaces are assumed to originate at the leading and trailing edges of the wetted surface. This report reviews and completes the basic theory and gives detailed examples obtained from the resulting parametric design technique. In the third design procedure, one specifies the design lift coefficient, the cavitation number and the upper cavity thickness at two points along the profile chord. A prescribed pressure distribution shape is also selected. The method also includes off-design calculations in accordance with the direct linearized theory of cavity flows which determines the flow states for which interference can occur between the upper surface of the cavity and the upper nonwetted surface of the profile. The hydrodynamic performance of specific point designs is also given by these direct calculations. The chief new feature of the third design procedure is the ability of the designer to prescribe two points on the cavity surface instead of one as heretofore.