3. A Method for Treating the Singularity at the Blade Tip of Marine Propellers
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概要
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Methods for calculating the hydrodynamic load distribution on the blade of marine propellers are discussed. The numerical solutions of the existing lifting surface theories do not converge at the round wing tip on account of the singularity. The restriction in the existing theories can be removed by using the new integral equation presented by Prof. Hanaoka. Employing the new integral equation, a numerical procedure is developed for the steady and unsteady propeller. In the present method, the range of validity of propeller lifting surface theory is extended to include the tip of blade The method is applied to an usual broad bladed propeller and to a highly broad bladed propeller. The result is compared with the calculations by the existing mode function method (series expansion method) and by the new doublet-lattice method. The new doublet-lattice method is the method devised to give the accurate solution near the leading edge. Following facts are revealed by the results of the numerical investigation. (1) Accurate solutions for the hydrodynamic load distribution near the tip of blades are obtained by the present method. (2) For the case of a highly broad bladed propeller, the existing series. expansion method is invalid and the present method should be used. (3) The present method is useful for the calculation of cavitation. (4) For the case of an usual broad bladed propeller, the existing series expansion method is valid in wide range up to 0.9 radius. The method is useful for the calculation of propeller forces. (5) The new doublet-lattice method gives the converged chordwise load distribution. The method is supposed to give the accurate solution near the leading edge and to be useful for the calculation of cavitation. (6) The effect of p^*≠p, that is, the effect of non-linearity in the steady theory on the characteristics of the unsteady propeller, is not small except the region near the tip of blade. The effect should not be neglected for the calculation of unsteady propeller forces. (7) A modification of the present method to shorten the computing time, is attempted. Further study must be continued on the modification.
- 社団法人日本船舶海洋工学会の論文
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- 3. A Method for Treating the Singularity at the Blade Tip of Marine Propellers