Abstract Trifoiler Paper SNAME

During the Fall of 1993, Greg Ketterman, the TriFoiler's designer, came to MIT for some advice. The TriFoiler seemed to reach an unsurmountable speed barrier around 44 knots, at which point the foils lost all their lift, and the boat came crashing down in the water. He suspected that at those speeds the foils were cavitating. I ran a series of tests in MIT Marine Hydrodynamics Water Tunnel, using a full scale sized foil of his boat. The results of these tests were presented at the New England Section SNAME Meeting.
Experimental and Analytical Investigation of a Cavitating Hydrofoil: The TriFoiler as a Case Study. C. Savineau, J. Paschkewitz. Presented at the New England Section SNAME Meeting, MIT. February 3 1994.

A full scale hydrofoil wing of a high speed sail boat was tested in MIT's Marine Hydrodynamics Cavitation tunnel. Force and flow measurements were made at several angles of attack, and cavitation numbers. Lift coefficients were calculated using load cell force measurements and were compared to lift coef calculated using momentum flux integration from flow measurements made with a Laser Doppler Velocimeter (LDV.) Cavitation growth with varying angle of attack and cavitation number was measured using the LDV. At low angles of attack, lift coef calculations were more reliable than direct load cell measurements. Performance curves were calculated to determine under what conditions the hydrofoil no longer performs to its design characteristics. Numerical calculations, using a low-order, potential-based boundary element method, were made to simulate the experimental conditions. The numerically predicted calculations for lift coef and cavitation number were in very good agreement with the experimental data. Relying on numerical simulations only, further in depth analysis and recommendations for foil design improvements are made