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This study investigates the feasibility of utilising common composite material layup techniques in ship propeller blade design to achieve an automatic pitch adjustment through bending-induced twist deformation. A comprehensive design approach, including various reinforcement materials and arrangements, was employed to attain the desired foil pitching, while minimising other undesirable deformation modes. The design process involved iterative computational analysis using finite element analysis and a deformation mode analysis based on foil shape parameters. The research showed that the proposed design approach effectively found options to improve the desired foil parameter pitch, while minimising undesirable deformation modes such as blade deflection and foil shape change. Furthermore, the proposed blade design was tested in thruster steering operational conditions and was found to have a pitch change well matched, potentially countering some changes in fluid flow. When compared to Kumar and Wurm’s design, which only focused on the angular orientation of glass reinforcement, the proposed design was found to outperform the twisting by achieving the same twist for a blade half the length. This study provides valuable insights into the utilisation of composite materials in ship propeller design and highlights the potential for further improvement through a composite engineering design approach.

Sloshing phenomenon consists in the movement of liquids inside partially filled tanks, which generates dynamic loads on the tank structure. Resulting impact pressures are of great importance in assessing structural strength, and their correct evaluation still represents a challenge for the designer due to the high nonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of air trapping. In the present paper a set of two-dimensional cases for which experimental results are available are considered to assess merits and shortcomings of different numerical methods for sloshing evaluation, namely two commercial RANS solvers (FLOW-3D and LS-DYNA), and two own developed methods (Smoothed Particle Hydrodynamics and RANS). Impact pressures at different critical locations and global moment induced by water motion for a partially filled tank with rectangular section having a rolling motion have been evaluated and results are compared with experiments.

This article presents a propeller ventilation model that is tuned on experiments performed in open water condition in a towing tank. The main purpose of performing the experiments was to obtain more data at higher advance numbers for validation purposes and to make a calculation model for thrust and torque loss due to free-surface proximity. Tests were performed at different draughts. For each draught, the propeller was tested at different propeller speeds n = 9, 12, 16, and, 16 Hz at advance number in the range from J = 0 to J = 1.0. The different advance numbers were obtained at different propeller speeds so that for the same advance number, different propeller thrust values were tested, so that the effect of propeller loading can be seen independently from the speed of advance J. The main focus of this article is to explain and validate a prediction model for thrust loss due to ventilation and out-of-water effect. 1. Introduction Ventilation is a phenomenon of air-drawing seen on structures operating below the free surface, such as hydrofoils, rudders, and propellers. Propeller ventilation is related to the propeller coming close to the free surface and "sucking" air into the propeller, or when the blades are piercing the free surface. In these cases, propeller ventilation leads to a sudden and large loss of propeller thrust and torque, which might lead to propeller racing and possibly damaging dynamic loads, as well as noise and vibration. Ventilation typically occurs when the propeller loading is high and the propeller submergence is limited, and when the relative motions at the propeller are large because of heavy seas. Propeller ventilation inception depends on different parameters, i.e., propeller loading, forward speed, and the distance from the propeller to the free surface, see e.g., Smogeli (2006); Koushan (2006a-c); Kozlowska et al. (2009); Califano (2011); Jermy and Ho (2008); Hough and Ordway (1965); and Kozlowska and Steen (2010).