Effect of Flaps on the Lift and Drag of a Surface-Piercing, Fully Ventilated Dihedral Hydrofoil

摘要

A surface-piercing, fully ventilated dihedral hydrofoil was tested to evaluate the effects of flaps on the lift and drag characteristics. The 30-degree-dihedral foil was equipped with a number of full-span flaps: two 25-percentchord flaps deflected 20 degrees and 40 degrees, and two 50-percent flaps deflected 10 degrees and 30 degrees. These configurations were operated over a speed range of 20 to 30 fps, at trim angles of 6 to 16 degrees, and at submergences of 1 to 3 chords. Finite-aspect ratio and free-surface effects were removed from the test data, through the use of techniques developed earlier in this series of studies on cambered and flat-plate hydrofoils. The corrected results thus obtained are compared with a two-dimensional non-linear theory at infinite submergence, and good agreement is obtained. A procedure is described which can be followed to predict the three-dimensional lift and drag, at finite depth, for a surface-piercing, fully ventilated, dihedral hydrofoil with flaps. (Author)