Modeling and Numerical Investigation of Aerodynamic Characteristics of a Propeller Circling on a Whirling Arm

A whirling arm is an effective device to measure propeller characteristics at low advance ratios. In the authors’ preceding research, an apparent advance ratio was adopted to determine propeller characteristics. The apparent advance ratio is determined only by the relative airspeed of the rotating arm and propeller in still air, and is used in wind tunnel measurements. However, in the case of whirling arm measurements, the advance ratio should be determined appropriately considering the additional airspeed induced by propeller wakes and swirling flow generated by the rotating arm. To address the above issue, we propose an airspeed model of blades considering velocity fields induced by the surrounding vortices. We also propose a procedure to calculate an appropriate advance ratio and the steady characteristics based on the proposed model. The validity of the proposed airspeed model is evaluated by making a comparison with the results of wind tunnel experiments. The corrected propeller characteristics using our airspeed model shows good consistency with the data referred from an existing propeller characteristics database.