Simultaneous Measurements of Pressure and Deformation on a UCAV in the SARL

Abstract

The assessment of advanced technology in the air force is becoming more reliant on the accuracy and fidelity of numerical predictions. It is expedient therefore, to validate the numerical codes upon which these assessments are based. The validation process requires the direct comparison of experimental measurements and numerical predictions. Among the issues that hinder the comparison of experimental measurements and computational predictions is the accuracy and structural integrity of the physical model. The ability to monitor the structural deformation of the model while simultaneously acquiring experimental data is of significant value. In an effort to resolve this issue, an experimental system that integrates Binary PressureSensitive Paint and Stereo Photogrammetry into a single system has been developed. Stereo Photogrammetry utilizes two images of the model to provide quantitative measurements of the displacement and deformation of the model surface. Pressure-Sensitive Paint allows nonintrusive measurements of pressure with high spatial resolution. Binary-Pressure Sensitive Paint uses a reference channel to compensate for errors that result from variations in temperature and illumination over the model surface. An added advantage of binary pressure-sensitive paint is the elimination of all but a single wind-off measurement, thus increasing tunnel productivity. Here we report the results of several experiments that demonstrate the capability of Binary PressureSensitive Paint in low speed wind tunnels. Finally, the integration of pressure and deformation measurements into a single system is demonstrated by experimental measurements of pressure and deformation on an Unmanned Combat Air Vehicle model in the Subsonic Aerodynamics Research Laboratory wind tunnel at Wright-Patterson Air Force Base.