Ventilated Propeller Blade Loadings and Spindle Moment of a Thruster in Calm Water and Waves

This paper presents experimental results of the forces and moments acting on a single propeller blade running in ventilated conditions in calm water and in waves. A model of a Rolls-Royce Azipull thruster with a four-blade propeller was tested with provisions to measure three orthogonal moments including spindle moment and two forces, on a single blade. The centrifugal force was not measured. High speed video is included to help gain a clearer understanding of the ventilation phenomena. The primary purpose of these tests is to establish a dataset for comparison with CFD calculations. They are also of use in structural design of propeller blades and improvement of dynamic positioning systems. Time averaged and dynamic measurements are presented, with the influence of various conditions such as static immersion, wave height, wave period, and propeller loading analyzed with respect to reduction in forces and moments. Comparisons are made with both ventilated and unventilated calm water cases.