Pages 91-105
Propeller wake trajectories of controllable pitch propeller (CPP) model were visualized by the air injection method and the solid particle tracer method over the wide range of operating conditions. The analysis of the wake data resulted that; (l) Even at the off-design pitch settings, the propeller wake forms thin vortex sheet as well as at the design pitch setting. (2) At any pitch settings the propeller wake can be devided into two parts. One is the inboard vortex sheet which has approximately same wake pitch as the geometrical pitch of the wing section where the wake flows out and another is the tip vortex near the blade tip whose pitch varies with the attack angle near the tip. (3) The variation of the wake radius depends on the propeller load. Based on the experimental wake data a CPP wake model is proposed. The geometry of the propeller wake can be drawn as functions of the propeller geometry and the propeller operating condition. Expressions of the wake model are presented in equations (6) to (18) in this paper. Both at the design and the off-design pitch settings the correspondence of the calculated wake geometry with the measured wake geometry is fairly good in spite of a relatively simple wake model.
