When a ship sails in an ice area, the ice could cause damage to ship hull and the propeller as well as the rudder. In the design process of an ice class propeller, the strength verification of the propeller has always been the focus of the design and research of the ice propeller. Based on the International Association of Classification Societies Unified Requirements for Polar Class (IACS Polar UR), it is required that the maximum torque from the propeller cannot exceed the required value to ensure the safety of the propeller shafting equipment. This paper investigates the hydrodynamic performance of the propeller under the condition of satisfying the propeller’s ice strength. A parametric propeller optimization design procedure was established in which the thrust coefficient and open water efficiency solved by CFD method were selected as the objective function and optimization target, the maximum ice torque was used as the optimization constraint under the condition that the ship’s shafting equipment remains unchanged, the propeller pitch, thickness, and camber at each radial direction were taken as the optimization design variables, and the optimization algorithm of SOBOL and NSGA-II was adopted. The interaction mode of propeller and ice was simulated by the method of explicit dynamics. The equivalent stress and displacement response of the blade during the cutting process of the ice propeller were calculated, monitoring the ice destruction process. The results show that the multi-objective Pareto optimal solution set of thrust coefficient and open water efficiency of the ice class propeller was formed at the design speed while maintain the maximum ice torque not exceeding the original ice torque.
The Energy Efficiency Design Index (EEDI) has been applied to ship carbon emission standards since 2013, ice ships subject to the Finnish Swedish Ice Class Rules (FSICR) also need to meet the requirements of EEDI. In this study, the engine power requirements by EEDI at different stages for the considered ice class ships with different ice classes (1C, 1B, 1A, 1A Super) are compared with engine power requirements obtained from the resistance calculated by FSICR or Lindqvist method. Three different bow shapes for the considered ice class ships and different pack ice coverage are studied. The results from FSICR or Lindqvist formula show that 1A Super ice classes for all considered bow shapes cannot meet the requirement by EEDI at Phase 2 and 3; For 1B and 1A class, some bow shapes can meet the EEDI requirement for all stages, but some cannot; For 1C class, all bow shapes can meet the EEDI requirements for all stages. The ship main engine power requirements under different pack ice concentration are studied and compared to EEDI requirements.
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