Film-based pressure-sensitive-paint measurements

A technique to measure surface pressure distributions by use of pressure-sensitive paint and a novel filmbased imaging system is described. An oxygen-permeable photoluminescent paint is excited by narrow-band light centered at 455 nm. The resulting red-shifted luminescence (>570 nm) is imaged with a 35-mm film camera and digitized with a film scanner. The luminescence is quenched by oxygen, resulting in a logarithmic relationship between film density and pressure. An image collected at a reference condition is subtracted from an image obtained at the test condition and calibrated with known pressures. The resulting images are, to our knowledge, the first quantitative global surface measurements made with pressure-sensitive paint by a film-based imaging technique.