Pressure sensitive paint measurements on a wing model in a low-speed wind tunnel

Pressure field measurements on a wing profile are conducted to evaluate the accuracy of a measurement system using the so called “binary” or “two-color” Pressure Sensitive Paint (PSP) for low-speed (40-60 m/sec) environments. A part of the wing surface was coated with a binary paint. Two different light sources, a high pressure Xenon-flash lamp and a nitrogen laser were used for the excitation of the paint. The resulting fluorescence fields were acquired by a 16-bit CCD slow-scan camera. In front of this camera two different optical devices, a filter-shifting system or alternative a beam-splitting system, each of them were equipped with appropriate optical filters to separate the two different spectral emission wavelength of the paint, were used. Results shows that this optical pressure measurement system is able to resolve the small pressure changes on the model surface. Due to model movement and model deformation in between the image acquisition of the “wind-off” and “wind-on” images the necessity to use a binary paint for precise pressure measurements is clearly visible. These PSP-System working with binary paint can achieve pressure resolution in the region of 1 mbar