Using Wave Propulsors of Different Types on Semisubmerged Catamarans

The article presents an overview of the studies carried out in the Institute of Mechanics of Moscow State University in 2021–2024. The results of experimental studies of the application of wave propulsors (WP) of the flapping wing type and direct-flow wave propulsors (DFWP) on a 1700 mm-long model of a small waterline area vessel (SWAV) are presented. The NACA0015 profile is used as a working element of both the flapping and direct-flow WPs. In the case of the direct-flow WP the profile is rigidly fixed against the hull with the wing chord inclination of 30°. The efficiency of using the WPs of the underwater sail type is also studied. Different WP types are tested on a smaller-scale DFWP model, 840 mm in length. Comprehensive studies of the efficiency of the direct-flow WPs and the underwater sail type WPs are carried out on a small model. An inclined plate is used as a working element of the direct-flow WP. The optimal parameters of the direct-flow WP (length, inclination, plate immersion) are experimentally determined. The effect of the hull immersion depth (draft) and the immersion depth of the underwater sail type WP on the vessel velocity counter waves is studied. The experiments show that the efficiency of flapping wings or underwater sail wave propulsors in the operating range of wave frequencies is slightly higher than that of DFWP. However, in stormy sailing conditions, DFWP has an advantage, since it shows the highest efficiency just in such conditions, while the other options considered are effective in the operating range of wavelengths that depends on the ship length and, generally speaking, does not coincide with the length of storm waves.