PSP systems determine air pressure by measuring the luminescencelifetime of an oxygen-quenched luminophor in a porous matrix. Whiletraditionally lifetime was inferred from measurements at differentpressures, it is becoming increasingly common to make direct lifetimemeasurements by taking images at different points on the luminescencedecay curve using a gated camera. Here, the accuracy of the lifetimemethod is evaluated through theoretical analysis, bench top studies, andsmall scale wind tunnel tests, with the primary aim of determiningwhether the lifetime method is suitable for measurements in very lowspeed flows (Mach~0.1). It is found that the luminescence lifetime of aPSP-coated surface can vary from point to point even at constantpressure and temperature. This variation is a significant source oferror in low speed measurements, and can be reduced significantly bycareful paint application procedures
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