Blade Tip Pressure Measurements Using Pressure-Sensitive Paint

This paper discusses the application of pressure-sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-Foot Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with pressure-sensitive paint measurements. The rotor had an 11.08 ft diameter, 5.45 inch main chord, and a swept, tapered tip. Three thrust conditions were examined in hover, C-T = 0.004, 0.006, and 0.008. In forward flight, an additional thrust condition, C-T = 0.010, was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.