Hydrodynamic resistance of a sail ship with tunnels and openings in the hull

Ovaj rad ispituje mogućnost ugradnje hidro-generatora u trup velikog jedrenjaka. Korištenjem računalne dinamike fluida (CFD) moguće je proračunati i analizirati hidrodinamičke značajke dovoljnom preciznošću u znatno kraćem vremenu u odnosu na pokuse s bazenskim ispitivanjem modela. U prvom dijelu rada su objašnjene mogućnosti svih relevatnih metoda i parametara za uspješno izvođenje numeričkih simulacija, kao što su metoda konačnih volumena, diskretizacija proračunske domene, matematički modeli, modeli turbulencije, RANS jednadžbe, metoda udjela volumena u fluidu te granični sloj i odgovarajući rubni uvjeti. Rezultati otpora forme jedrenjaka, dobiveni primjenom računalne dinamike fluida, uspoređeni su s dostupnim eksperimentalnim rezultatima u svrhu validacije metode. Istim postupkom proračunate su značajke strujanja i određene hidrodinamičke performanse jedrenjaka s izmijenjenom formom krme. Kako nisu poznate slične instalacije na brodovima, početne dimenzije tunela i otvora u trupu uzete su prema dostupnim dimenzijama postojećih vodomlaznih propulzora. Proračuni hidrodinamike su izvođeni kao da se radi o ugradnji takvih propulzora. Na taj način dobiveni su podaci o strujanju, poljima brzina i tlakova na lokacijam na trupu. Analizom tih podataka može se utvrditi najbolja lokacija za smještaj otvora i tunela, a sa stajališta manjeg otpora broda kod ugradnje bilo vodomlaznih propulzora ili hidro-generatora.This thesis examines the possibility of installing a hydro-generator in the hull of a large sailing ship. Using computational fluid dynamics (CFD), it is possible to calculate and analyze hydrodynamic characteristics with sufficient precision in a significantly shorter time compared to experiments and model testing. The first part of the thesis explains the possibilities of all relevant methods and parameters for successful numerical simulations, such as finite volume method, domain discretization, mathematical models, turbulence models, RANS equations, fluid volume fraction method and boundary layer and corresponding boundary conditions. The resistance results of the sail ship hull form, obtained by applying computational fluid dynamics, were compared to the available experimental results for the purpose of method validation. The same procedure was used to calculate the flow characteristics and to determine the hydrodynamic performance of sail ship with a modified stern shape. As similar installations on ships are not known, the initial dimensions of the tunnels and openings in the hull are taken according to the available dimensions of the existing water jet propulsors. Hydrodynamic calculations were performed as if it were the installation of such propulsors. In this way, data on flow, velocity and pressure fields at hull locations were obtained. The analysis of these data can determine the best location for the location of openings and tunnels from the point of view of lower resistance of the ship when installing either water jet propulsors or hydro-generators