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-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, CT = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, CT = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.