Image based measurement techniques for aircraft propeller flow diagnostics -Propeller slipstream investigations at high-lift conditions and thrust reverse-

Abstract

From time to time when oil prices increase, propeller research revives. Advanced turboprops (‘propellers’) are from a point of view of fuel efficiency advantageous over standard turbofans and because of this advantage future propulsive concepts will involve ‘open rotor’ designs. Propeller designs are complex in terms of fluid-structure (i.e. wing-vortex) interaction and fluid-noise interaction. Such aerodynamic complexity is one of the main reasons why ‘open rotor’ concepts never had their break through. The current usage of advanced measurement techniques for turboprop designs in aeronautical applications is rather minimal. In order to appreciate the finer details of propeller vortex evolution, and to be able to address these phenomena in the future for advanced concepts, advanced measurement techniques should be applied to turboprop investigation beforehand. Advanced visualization techniques such as Particle Image Velocimetry (PIV) and Background Oriented Schlieren (BOS) have several advantages over ‘standard’ wind tunnel techniques. Yet, those techniques are not widely used for the investigation of aeronautical propeller phenomena.