Numerical Investigation of Propeller-Ice Interaction Effects

Abstract

Within the framework of German national funded research project ProEis, focusing on the propeller-ice interaction, an innovative numerical tool has been developed to assess the effects of such phenomenon on the loads acting on the propeller and on its propulsive efficiency. The proposed methodology is to calculate the loads on the propeller as the sum of the separable hydrodynamic loads, the inseparable hydrodynamic loads and the ice contact loads. The separable hydrodynamic loads are the loads acting on the propeller in ice-free water whereas the inseparable hydrodynamic loads act on the propeller due to the ice blockage effect. Both of these loads are calculated by a panel based code. The loads originating from the physical contact between ice particles and the propeller, called the ice-contact loads have a significant contribution to the total loads acting on the propeller. They are calculated using the empirical formulae as given by Wang J. (2007), subdividing the physical propeller-ice interaction into crushing and shearing phenomena. Several interaction scenarios (size, location and strength of ice piece(s)) are modeled & compared and the effect of various parameters is quantified. The numerical tool is calibrated from the results of a model test campaign focused on propeller-ice interaction and in which a linear feeding device is used to guide ice floes into a model propeller to be milled under controlled conditions. Milling tests have been carried out both in the water and in the air, in order to identify the contribution of each type of load to the total load measured on the propeller. The report ends with conclusions and suggests further work to be performed in order to enhance the numerical model.