Propeller Design and Propulsion Concepts for Ship Operation in Off- Design Conditions

Ship operators are calling more often for reduced fuel consumption and economic ship operation also in offdesign. The versatile operation profile of ship types such as RoRo-vessels are then a challenge for the design of the propeller and for the propulsion concept. This paper presents aspects on the propeller design and propulsion concept of a ship as well as design methods for the propeller. Long-term recordings of operation parameters such as pitch setting, propeller revolutions, speed and rudder angle on board of a ship are presented to give an example on a realistic operation profile and its impact on the propeller design. In addition, design methods for controllable pitch propellers are presented as well as hydrodynamic methods: Calculations with a vortex-lattice method and RANS solutions of a propeller with different pitch settings are compared with model tests and with full-scale measurements. The prediction of the slipstream of the propeller is also important for the rudder design. An unsteady RANScalculation of a propeller working in the wake of a ship is compared to PIV-measurements in planes behind the propeller.