PREDICTIONS OF ICE CONTACT FORCES ON A MARINE SCREW PROPELLER DURING THE PROPELLER-ICE CUTTING PROCESS

A model is developed that simulates the process that occurs when a marine screw propeller and a submerged ice body come into contact. The time simulation predicts the ice contact forces acting on a propeller blade and the motion response of ice. The equations of ice body motion are a system of six nonlinear ordinary differential equations for rigid body motion. These are solved time-stepwise with a numerical integration routine that forms the core of a simulation model. The propeller is treated as a rigid body with constant rotational and translational velocities. Propulsion machinery and shafting are ignored. The ice body shape is idealized as spherical and changes in mass due to cutting are ignored. A propeller-ice contact model, based primarily on laboratory ice cutting experiments, is developed. An inference drawn from the experiments is that contact during ice cutting is concentrated near the propeller blade's leading edge. Ice failure on the pressure side (face) of the blade is characterised by an ice chipping process. Intermittent propagation of cracks from near the leading edge contact zone to a free ice surface severely limits the extent of contact on the pressure side. On the suction side (back) ice failure mainly is due to the coalescence of numerous small cracks or crushing. The progressive crushing on the suction side and chipping on the pressure side are repetitive processes. Simulation model results are presented for propeller-ice interaction events over a systematically varied range of parameters. Comparisons of simulated events in which the ice was first free to move and then fixed in space indicate that the effect of ice motion is to reduce the severity and duration of contact loads. The operating conditions of the propeller and the size of the ice are important parameters influencing propeller loading. This prediction model can be used to improve propeller blade and propulsion system design.

• Supplemental Notes:
  • Acta Polytechnica Scandinavica, Mechanical Engng Series n 118, 1995 [140 p, 91 ref, 5 tab, 60 fig]
• Authors:
  • Veitch, B
• Publication Date: 1995

Language

• English

Subject/Index Terms

• TRT Terms: Ice; Mathematical models; Propellers
• Old TRIS Terms: Ice forces; Propeller ice interaction
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00733256
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Mar 27 1997 12:00AM