Numerical prediction of model podded propeller-ice interaction loads

As the interest in arctic shipping and arctic exploration of oil and gas is increasing in recent years, the number of ice class vessels is increasing rapidly. Also the choices for propulsion devices are getting wider and these include podded propulsion systems. This study is a framework for the numerical prediction of the ice interaction loads acting on a podded propeller blade. The results of this study will help us to understand the propeller-ice interaction problem more comprehensively. Several studies for propeller-ice interaction have been carried out in past few decades. Propeller-ice interaction, however, is a complicated process with a high level of uncertainties due to ice properties, ship operating conditions, and environmental conditions. Full-scale measurements involve high costs. In order to overcome these difficulties, model tests were carried out with model ice in an ice tank. The model tests provide well-controlled ice properties and interaction conditions to reduce the uncertainties. The tests were carried out in the ice tank with scaled down model ice at the National Research Council of Canada?s Institute for Ocean Technology. The ice loads acting on the propeller blade were measured with a six-component force and moment load cell fitted to one of the propeller blades. Based on the experimental results, a numerical prediction model was developed to estimate the ice loads on the propeller blade. The numerical prediction is composed of two parts: the hydrodynamic calculation, and the ice milling load calculation. The hydrodynamic calculations, i.e. propeller performance in the clear water are done by using a low order panel method. The subroutines for calculating the ice milling loads are implemented into the panel method. Several previous empirical formulae for prediction of ice loads are introduced and modified for this study. The new numerical prediction model for ice milling loads is described and compared with previous models and experimental results.Peer reviewed: YesNRC publication: Ye