변분 원리를 응용한 타에 부착된 Post-Swirl Fin의 최적 설계에 관한 연구

This study treats an application of variational principle to the design of post swirl fins which develop additional thrust from propeller slip stream. The design problem is formulated with the vortex lattice lifting line representation of the components so that the power absorbed by a propeller is minimized with the thrust generated by the propeller and fin given by a prescribed value. The optimum circulation distribution of each component is determined by solving a resulting discrete variational problem. The interactions between the two components are considered in circumferentially averaged velocity field calculation at one component location induced by the other one. The procedure is first applied to the determination of the optimum single propeller loading distribution and compared with the Lerbs solution in open water configuration. The developed method is then applied to the design of the propeller and post-swirl fins attached to rudder for a VLCC. To verify the velocity field calculations, flow measurement is conducted behind a propeller. Finally self propulsion tests are carried out to estimate the efficiency increase by the fins. The result proves the validity of the design procedure.