Fast Pressure-Sensitive Paint System for Production Wind Tunnel Testing

Significant advances in the use of fast responding Pressure-Sensitive Paint have recently been achieved as demonstrated by a multi-camera fast PSP test conducted in the 16 foot transonic wind tunnel at AEDC. The unsteady pressure results from this test demonstrated excellent accuracy and spatial resolution, establishing the technical readiness of the fast PSP sensor. During the program, two issues were identified that would significantly improve the fast PSP system performance, 1) real-time data processing, and 2) acquisition of both mean and unsteady data using a single entry. Here we propose the continued development of the fast PSP system by addressing these issues. To enable real-time data processing, a system composed of a computer with a large block of memory, a multi-core processer, and several high end video cards (GPUs) has been assembled. Modern GPUs include thousands of floating point processors and large blocks of memory which enable parallel computations to be executed on individual images. Fast PSP data is an ideal application of this technology as many of the computations can be performed on each image independently. Preliminary tests by ISSI have demonstrated improvements of a factor of three to thirty in processing time using this approach. Acquisition of both mean and unsteady pressure during a single tunnel entry would increase tunnel productivity and can be used to improve the accuracy of the unsteady pressure data. Unfortunately, fast PSPs are generally very temperature sensitive which limits their use in acquiring mean pressure data. ISSI has recently developed a fast PSP formulation with low temperature sensitivity. This formulation will be optimized for use in large wind tunnels and enable acquisition of mean and unsteady pressure data using a single PSP.