ДОСЛІДЖЕННЯ МОРЕХІДНОСТІ РИБАЛЬСЬКИХ СУДЕН ЗА ДОПОМОГОЮ CFD МЕТОДІВ

Abstract

Seakeeping performance is quite important for certain ship types. Fishing vessels often operate in areas with frequent storms, and sometimes it is necessary to continue fishing despite the worsening sea state. The development of hull forms providing good seakeeping performance of fishing vessels is the problem of current interest in ship design. The conventional approach to seakeeping studies is testing models in ship model basins. However, it is time-consuming and expensive, especially when many hull form variants are studied. For this reason, computer calculations based on the theory of ship motions and strip theory were developed and introduced. Today the more advanced methods of computational fluid dynamics (CFD) can be applied to the problem. The study of ship motions with the help of Reynolds-averaged Navier-Stokes (RANS) CFD method is considered in this paper. A suggested numerical model implies the generation of waves through initial and boundary conditions, which express fully developed waves with preset parameters. An object of research is the seagoing trawler with an overall length of 44.6 m. Three versions of hull form are used in simulations. All versions have similar transom afterbodies, but different forebodies: one similar to Axe Bow, a bulbous bow and one similar to X-bow. Ship movement with headings 180° and 150° at speed of 3.5 knots was studied to reveal differences in added resistance and ship motions. While added resistance and characteristics of heaving and pitching have shown no clear advantages among the considered shapes of forebodies, the version similar to X-bow has demonstrated a significant decrease in rolling at heading 150°. The results of the study have shown that the suggested numerical setup in combination with the CFD methods described can be used for quite realistic simulations of ship behaviour in rough seas. Keywords: seakeeping simulations, seakeeping of fishing vessels, CFD for ship design, improved seakeeping performance, simulation of ship motions.