RESEARCH ON CONTACT JUDGMENT OF ICE-PODDED PROPULSOR BASED ON NUMERICAL METHOD OF PERDYNAMICS

The ice-going ship with podded propulsor can avoid maneuverability problems, such as changing direction, turning round and so on, when navigating in the ice-covered waters. Therefore, the podded propulsor is widely used in ice-going ship. In the milling process of ice-podded propulsor, podded propulsor is subjected to extreme ice load, which brings serious harm to the structural strength of podded propulsor and the safety of ice-going ship. In order to study the change regularities of ice load in the process of podded propulsor with different maneuvering states and ice milling, first of all, the theoretical basis of the peridynamic method to study the fracture problem of objects is introduced in detail in the paper, and the feasibility of the method to simulate ice material is analyzed. Based on the coupling of the peridynamic method and the panel method, the material failure criterion for ice breaking simulation and the ice load calculation method suitable are derived. Secondly, a method to judgment the contact between podded propulsor with different maneuvering states and ice in the milling process is proposed. The numerical calculation model of ice-podded propulsor milling state is established, and the numerical simulation of ice-podded propulsor milling dynamic process is realized. Finally, the changes of ice breaking, ice load of propeller and single blade, overall torque of podded unit during podded propulsor with straight ahead, azimuthing condition, dynamic azimuthing condition and ice milling are analyzed. The results show that the contact judgment method proposed in this paper can real simulate the milling process of the ice-podded propulsor, and obtain the ice breaking phenomenon and ice load variation characteristics in the process. It can provide guidance for the development of numerical prediction technology for ice load on marine structure in ice area, the optimization design and operation of ice class podded propulsor.