BOS measurements in propeller slipstream

The background oriented Schlieren (BOS) method has been used to qualitatively identify the density gradients in the helical structure of a propeller slipstream. The applicability of the BOS method to rotational flows has been identified by Richard et al. (2000). Recently Kindler et al. (2007) have used a tomographic reconstruc-tion in order to estimate the density and core ra-dius of rotor flow. From an aerodynamic point of view the propeller wing interaction remains an avid field of investigation (Veldhuis, 2005). The current BOS measurements investigate vor-tex structures in a propeller slipstream at two sideslip angles, 0° and 7°. An 8-bladed single sting propeller is mounted to the wind tunnel ceiling. A total of 200 images are recorded at each angle. Reference images of the background are recorded with the propeller removed and the wind tunnel flow off. The propeller rotates at 14000 revolutions per minute; the wind tunnel velocity was 60 m/s