Optical Based Pressure Measurements in Aerodynamic Flows Using Fluorescence Lifetime Imaging

Optical techniques employing photoluminescent pressure-sensitive paints provide versatile tools for obtaining pressure maps of the aerodynamic surface. These techniques do not distort the flow field like arrays of pressure transducers or pressure taps on the test surface, and they provide high spatial resolution, accuracy and rapid response. Current techniques based on the fluorescence intensity have a number of shortcomings, however, which can be overcome by imaging the spatial variation of the lifetime of the fluorescence. Lifetimes are immune to spatial variations in the uniformity of the paint, spatial alignment errors between wind on and wind off conditions, and variations in excitation intensity. Lifetimes are also insensitive to contamination and photodegradation of the paint. Systems & Processes Engineering Corporation (SPEC) proposes to develop a rugged fluorescence lifetime imaging (FLIM) system which will provide high-resolution surface pressure maps for a wide variety of test and development facilities. SPEC will work with Dr. Martin J. Morris of McDonnell Douglas Corporation to devise a plan for integrating the instrument into typical aerodynamic test/development facilities. To further optimize the system SPEC will work with Dr. Gabor Patonay of Georgia State University and Dr. Morris to formulate a highly efficient pressure sensitive paint. Implementation of the FLIM system will allow rapid improvements to the aerodynamic design of both military and commercial aircraft. The FLIM system may be used for optimizing the aerodynamic design of bridges and buildings in hurricane-prone regions. The system may also be used for the hydrodynamic design of both surface ships and submerged vessels. The use of Dr. Patonay's NIR dyes will allow for the development of a new class of MIR dyes for a variety of applications FLIM systems based on these NIR dyes may allow the early detection of diseases, biological hazards, and structural monitoring.