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Published February 1985 | Published
Journal Article Open

A performance-prediction theory for partially submerged ventilated propellers

Abstract

A partially submerged propeller theory was developed by employing a singularity distribution method. Unsteady pressure doublets and pressure sources represented the blade camber and blade-and-cavity thickness respectively. The induced velocities were derived by reducing the formula to a lifting-line configuration. The free-surface effect was considered by use of the image method. The induced velocities contained the singular integrals of 5th order, which are usually numerical unstable. An effort was made to derive numerically stable formulae from these singular equations by applying a method similar to the induction-factor method of Morgan & Wrench (1965) and Lerbs (1952) used for steady-state fully wetted propeller problems. These new formulae are not only applicable to the present partially submerged ventilated propeller problem, but also to general unsteady subcavitating and cavitating propeller problems such as propeller starting-up and non-periodic loading problems. By combining the two-dimensional water entry-and-exit theory of Wang (1979), the thrust and torque coefficients were calculated for representative partially submerged propellers and favourably compared with the experimental data.

Additional Information

© 1985 Cambridge University Press. Received 6 February 1984 and in revised form 23 April 1984. Published online: 20 April 2006. This project was supported by the David W. Taylor Naval Ship Research and Development Center of the U.S. Navy, under Contract No. N00167-80-C-0044. The author thanks Dr W. Morgan, Messrs D. Cieslowski and V. Monacella of NSRDC and Dr D.P. Wang for various support.

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Created:
August 19, 2023
Modified:
October 17, 2023