Investigation of the Propeller Slipstream with Particle Image Velocimetry

The flow around an 8-bladed propeller is analyzed using particle image velocimetry in the Airbus low-speed wind tunnel facility in Bremen, Germany. The propeller is mounted on a half-model equipped with two propellers with opposing rotation directions, where only the outboard propeller is investigated. For two cases with no thrust (C T = 0) and with thrust (C T = 0.1) the propeller slipstream is visualized at several angles of attack. In particular, the development of the slipstream over the wing is investigated with particle image velocimetry derived variables such as mean velocities, fluctuations, and turbulent kinetic energy. A detailed description of the slipstream returns valuable information on the vortical structures and periodic phenomena. An identification of such events is necessary for a future validation with numerical data. It allows for the analysis of parametric cases; first, a comparison between the thrust and no-thrust cases and, second, the effect of an increasing angle of attack. It is found that at the thrust cases, for higher angles of attack, vortices are formed due to interactions in the boundary layer.