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Justification of main characteristics of river-sea dry-cargo vessels with extra-full hull forms
Published in Petar Georgiev, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2019
G.V. Egorov, V.I. Tonyuk, A.G. Egorov, I.F. Davydov
Architectural-structural type of RSD59 vessel is steel single-deck, motor ship, with two full turned rudder propellers, with two cargo holds, with forecastle and poop, with living deck-house and engine-room located aft, with parallel middle body, with bulbous bow and transom aft end with semi-tunnels and skeg, with lift-away type hatch covers, with bow thruster. (see Figure 6).
Pre- and post-swirl fins design for improved propulsive performances
Published in Ship Technology Research, 2022
Stefano Gaggero, Mattia Martinelli
When analysed in terms of thrust, the results of the design process are not particularly exciting. The optimal geometry provides a negligible amount of additional thrust (few hundreds Newton) compared to the ship resistance, which is then reduced by the action of the ESD only of about 0.5%. Port and starboard fins of this optimal configuration have different spans. That on the starboard side is the longer and has its maximum geometric angle at tip. This is the fin that operates in the outer flow, less influenced by the shadowing effect of the hull/skeg, which instead could have a larger influence port side fin, that indeed is shorter and has the maximum swirling angle at the root (Table 2). Camber has the same sign on both sides, meaning that the prevalent flow is directed downward for both the fins as a consequence of the non-exact alignment between the propeller shaft and the ship rudder to which they are joined.
The use of computational fluid dynamic technique in ship control design
Published in Ships and Offshore Structures, 2021
M. Martelli, D. Villa, M. Viviani, S. Donnarumma, M. Figari
The cross-flow drag force is reproduced using (6), in which red terms identify the variation concerning the original formulation.The values of two longitudinally different coefficients need to be determined: and . The first one represents the sectional force developed by the ship when only a pure sway condition is considered, the latter (added respect to the original model) corrects the force when the local velocity is generated by a yaw rotation. In addition, also the draft has been kept constant respect to the original formulation where it changes with . Figure 10 reports the two obtained longitudinal distributions. The first one shows the typical lateral forces distribution with an increased crossflow coefficient for bow and stern zones; this is in line with literature data and formulations, which normally highlight that the sectional force is higher when the ratio is higher (as in the extreme parts of the hull). Furthermore, the force is larger in the stern region due to the presence of the skeg. Regarding the second parameter , a value equal to 1 corresponds to the original formulation proposed in Oltmann and Sharma (1984); it is clear that the phenomena cannot be simply considered as proposed, highlighting that flow is different moving from pure drift case to rotations.
Material quality effects on structural design of rudder horns for bulk carriers and tankers
Published in Ships and Offshore Structures, 2020
K. Tsevdou, P. Contraros, E. Boulougouris
Rudders can be classified according to the position of the stock (unbalanced, semi-balanced, or balanced) or the structural rudder – hull connection (the number of pintles, without skeg, semi-skeg, or full-skeg) (Liu and Hekkenberg 2017). According to Molland and Turnock (Molland AF, Turnock SR, 2007), rudder type choice depends on the ship type, the size of the ship, the shape of the stern, and the require rudder size. This paper presents a study on a semi-balanced rudder, which is the most commonly used in bulk carriers and tankers and reports an assessment of its strength, deflections and fatigue life, and the effects of using 4 different types of steel.