cntTSP visualization technique for rotating blade surface flow at low Reynolds number

Research and development of aircraft with rotating wings at low Reynolds numbers have received much attention. This study proposes using a carbon nanotube temperature-sensitive paint (cntTSP) measurement technique to visualize the surface flow of rotor blades at low Reynolds numbers. Temperature-sensitive paint (TSP) can optically measure a two-dimensional temperature field using the thermal quenching of luminophores. A carbon nanotube thin layer is used to heat the TSP layer in cntTSP measurements. For the experimental condition, the low Reynolds number at 75% of the rotor radius was 1.1 × 10⁴, and a blade tip speed of 7.2 m/s. Temperature distributions showing a leading edge vortex (LEV) were observed in the visualization results. Furthermore, the LEV region expanded from the wing-tip side to the wing-root side at high-pitch angles. These visualization results show the applicability of the cntTSP measurement technique for investigating the surface flow field of rotor blades at low Reynolds numbers.