Preliminary results of the first multiple image-based measurement campaign for the as-sessment of propeller slipstream properties on the BNF wind tunnel model

In order to alleviate cities and their citizens from aircraft noise an aircraft has been designed which should enable quiet, efficient, short take-off and landings (QESTOL) within the German research project ‘Bürgernahes Flugzeug (BNF)’ (translated: citizen friendly airplane). The various experimental aerodynamic aspects are investigated for a large part within the DLR project ‘SAMURAI’ which is dedicated to the simultaneous application of multiple image-based measurement techniques, such as (stereoscopic and tomographic) Particle Image Velocimetry (PIV), Background Oriented Schlieren (BOS), Projected Pattern Correlation (PROPAC), Temperature and Pressure Sensitive Paint (TSP/PSP) and acoustic array techniques. These image-based measurement techniques have been applied for the investigation of the propeller effects of the BNF aircraft. Non-intrusive image-based measurement techniques are advantageous for the investigation of highly rotating flows and are particularly useful for the investigation of effects such as thrust reverse or propeller slipstream structures. In addition to an experimental investigation are such datasets of importance for the validation of numerical codes. The current paper discusses several measurement tech-niques which have been applied during one wind tunnel entry for the investigation of several propeller induced proper-ties. The propeller slipstream and the active flow control have been analyzed with mono- and stereoscopic Particle Image Velocimetry (PIV). The helical structures at the in-board section of the propeller slipstream have been visualized with the Background Oriented Schlieren (BOS) method. Finally, the propeller blade bending and torsion are investigated using Projected Pattern Correlation (PROPAC)