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