Study on a Cavitating Hydrofoil having a Practical Blade Profile Shape.
Abstract
Experiments were conducted at the High Speed Water Tunnel of the California Institute of Technology for measuring the flow characteristics of a single foil over a full range of cavitation numbers. The blade profile shape used is that of a modified Tulin two-term camber with a blunt trailing edge. This profile shape was taken after the cross-section profile of a supercavitating propeller designed for an actual high speed hydrofoil boat. It was discovered in the experiments that the flow pattern totally changed at about an incidence angle of 2 degrees. For higher incidence angles than 2 degrees, the cavity sprang from the leading edge as was expected, whereas for lower incidence angles the base cavity and sometimes double cavities appeared. The trends of the force coefficients for these different cavity-flow patterns were, of course, found to be totally different. This fact, which was never considered in the design procedure nor in the off-design prediction theory, might have caused an erroneous prediction for the thrust coefficient and efficiency of this supercavitating propeller. In order to make comparisons with the experimental data, three new nonlinear cavity flow theories have been developed, one for the supercavitating (S/C) regime and two for the partially cavitating (P/C) regime. The results of these theories compared favorably with the experimental data, but the accuracy degraded as the cavity length became close to the chord length both in S/C and P/C ranges. The success of the present experiments has allowed us to design dummy blades for the cascade experiments to be conducted in the following phase of the present work for FY 1981. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 31, 1980
- Accession Number
- ADA095565
Entities
People
- Okitsugu Furuya
- Shin Maekawa
Organizations
- Tetra Tech