Propeller ice load models

Models for calculating the loads that a marine screw propeller experiences during ice propeller interaction are developed. The interaction process and various contact geometry and interactions types are described. Some laboratory and full-scale experiments are briefly presented. The interaction process is described with a simulation model. The model calculates the ice block/propeller contact geometry at each time step. The load balance between the blade and the block is based on a contact load model and a model of hydrodynamic disturbance loads caused by the presence of an ice block. This load balance affects the relative velocity between the ice block and propeller and accordingly the contact conditions for the next time step. The essential elements of the simulation model are given in this report. The contact load model and hydrodynamic disturbance load model are briefly described. The models are verified against some full-scale events. A set of parameter variations are studied with the simulation model. Finally the results of these parameter runs are condensed by means of regression analysis to simple load calculation formulas. The input parameters for these formulas are limited to those that are considered most essential.