Simultaneous pressure and deformation field measurement on helicopter rotor blades using a grid-pattern pressure-sensitive paint system

A grid-pattern pressure-sensitive paint (grid PSP) system is developed and then integrated with a stereo vision system to achieve simultaneous pressure and deformation measurements on rotating surfaces. The grid PSP features a dot pattern, which is prepared by spraying PSP dots on top of a polymer-ceramic binder. A single-shot lifetime method is adopted to obtain the transient pressure field on a rotor blade coated with PSP. Meanwhile, the PSP dots provide feature points for blade surface reconstruction through stereo cameras. A data processing algorithm is developed for calculating the blade motion angles based on the registration targets. This system was applied on a helicopter model test stand to capture a sequence of images on the rotating blade surface. The results from grid PSP were compared with regular PSP to evaluate the performance of pressure measurement. The accuracy of blade motion measurement was also evaluated for pitch angle from 15° to +15°, flap angle from −10° to +10° and lag angle from −10° to +10°, respectively.