Resolving vortex-induced pressure fluctuations on a cylinder in rotor wake using fast responding pressure-sensitive paint

摘要

The interaction between rotor wake and a cylinder has been studied experimentally in the current work. The cylinder was placed in close proximity to the rotor plane, and the pressure fluctuations induced by the rotor wake on the cylinder surface were measured by microphones and fast responding pressure sensitive paint. Based on the developed data processing methods, challenges such as the low signal-to-noise ratio were resolved and small pressure fluctuations (less than 100 Pa) during the interaction were successfully extracted. The high-resolution vortex-induced pressure field under different blade cylinder separation distances and rotor collective pitches were compared and analyzed, which clearly showed the effects of tip vortex strength and its evolution. More importantly, for cylinders with different cross section shapes, the pressure footprints left on the surface showed significant distinction in both pressure patterns and overall fluctuation levels. The flat surface would break the structure of the tip vortex and lead to both pressure rise and drop on the surface, while wedge-shaped obstacles would cut the vortex in half and result in two strong pressure drops on both sides. The square cylinder with a 0 installation angle (parallel to the blade) generated the least amount of pressure fluctuation due to its capability of fully breaking the vortex structure during the interaction. Published under license by AIP Publishing.