Cavitation erosion risk assessment on a full-scale steerable thruster
Themistoklis Melissaris (Wärtsilä Netherlands BV, TU Delft - Ship Hydromechanics and Structures)
Sören Schenke (TU Delft - Ship Hydromechanics and Structures)
Norbert Bulten (Wärtsilä Netherlands BV)
Tom J.C. van Terwisga (Maritime Research Institute Netherlands (MARIN), TU Delft - Ship Hydromechanics and Structures)
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Abstract
Propeller cavitation erosion prediction at an early design stage is becoming more and more important since it is one of the key constraints in the search for maximum propeller efficiency. Despite the experience from model tests, cavitation erosion research on actual ship scale is very limited. In this study, an attempt is made to assess the erosion risk on the blades of a full-scale steerable thruster of a tug boat. Pressure side cavitation was detected on board for three different propeller designs. For the first time, a cavitation erosion analysis is performed on ship-scale, using a rigorous potential energy approach, which accounts for the focusing of the potential energy at the collapse center during the cavity collapse. A full sensitivity study has been performed for the blade surface accumulated energy. The erosion model shows the erosion risk for different propeller designs applied on the vessel, and different operating conditions, by looking at the surface specific energy on the blade. The erosion analysis shows locations of high erosion risk that show a good resemblance with the actual damage locations on the real blades.