The numerical investigation of spindle torque for a controllable pitch propeller in feathering maneuver

Present paper studies the variation of the blade spindle torque in a controllable pitch propeller (CPP) during the feathering maneuver, which is one of the rare but most challenging propeller maneuvers in CPP operation. The knowledge of the spindle torque under different operating conditions is one of the key features for the CPP controller unit design. The aim of this study is determining the forces needed to be governed to control the blade motion of a CPP converted from a fixed pitch propeller and the scale effect on these forces. So as to obtain a realistic numerical setup, the time-dependent superposed motion of the main rotation of the propeller and the rotation of each blade around its axis is modeled using a hybrid overset/sliding mesh technique. The spindle torque values were calculated during the dynamical variation of the blade pitch in feathering maneuver, and a novel expression is recommended to non-dimensionalize the predicted spindle torque. The result revealed that the required torque values to rotate each blade during the propeller maneuver is rising up to a critical pitch angle. Further increment of the pitch angle results in lower spindle torque values. Furthermore, this critical pitch angle is inversely proportional to the propeller loading.