Experimental study on the wake fields of a ship attached with model ice based on stereo particle image velocimetry

Abstract

In this study, a 76000 DWT 1B ice-class Panamax Bulker attached with model ice was used as a test system for measuring the nominal wake fields based on underwater stereo particle image velocimetry. The results show that: The attached ice block adds a “virtual thickness” to the ship's stern that is equal to the thickness of the ice blocks. The interferes between ice blocks and ship's wake field results in significant expansions of the ship's axial velocity contours compared with the ice-free state, which also leads to the formation of severe velocity blockage zones (with u/U < 0.1) within the wake field against the incident flows of the propeller. The attachment of model ice to hull leads to interference in the stern's wake fields, and disrupts the streamlined in the vicinity of the hull. Furthermore, the non-streamlined shape of the model ice generates complex vortices that interfered with the bilge vortices of the bare hull. The level of interference varies according to the size and distribution of the model ice attachments, and the bilge vortices tends to weaken or shift outwards. Then, the test data were corrected based on momentum theory to be more close to the real phenomena.