Overview of industrial propeller measurements using PIV

Abstract

Image based measurement techniques like Particle Image Velocimetry (PIV) and Background Oriented Schlieren (BOS) provide instantaneous distributions of velocity, and density gradients, respectively. This makes them extremely useful tools that produce high quality data which can be used for validation purposes. Current propeller applications for military aircraft will be operated under various conditions that encounter high power settings (high thrust at take-off and during steep climbs) and large angle of attacks (particularly in drop configurations at reduced speeds, or during landing). Consequently, the propeller disk loading (i.e. the thrust divided by propeller disk area) is very high under such conditions. Available engineering tables and propeller theories can only determine the propeller slipstream to a limited extent for such conditions. Both methods have been applied in various industrial projects in order to study the flow field behavior and phenomena of a propeller aircraft. The dedicated measurements have been performed on a single-sting propeller as well as a half-model. Of interest was the development of the vorticity at different disk loadings, the slipstream contraction, flow field phenomena at propeller thrust reverse and the evolution of the vortex development. The later has been used for validation of computational fluid dynamic results.