Measurements of Controllable Pitch Propeller Blade Loads in Turns

To improve the prediction of the alternating blade loading under ship turning conditions, a test was conducted in a rotating arm facility, where propeller hub loads were measured on a combatant propeller/hull configuration. To obtain the alternating blade forces, three propeller configurations were tested: the baseline five bladed prop, a one bladed version, and a four bladed version (one blade removed). Care was taken to account for propeller imbalance, and centrifugal effects on loads. PIV was also used to measure the propeller inflow. The measured alternating blade forces were analyzed relative to the earlier tests of Boswell1. Also the measured inflow was used to compare load predictions to the measured results. Detailed analysis was performed to validate the use of both a single bladed and a four bladed prop to derive the single bladed forces.