Step response of pressure-sensitive paints

An experimental and analytical characterization of the response of three typical pressure-sensitive paint (PSP) formulations to a step change in pressure is presented. The three PSP formulations tested have all been previously used in wind-tunnel experiments and have been shown to have acceptable aerodynamic surface properties and mechanical durability. The time response of the PSP coatings is dependent on the diffusion of oxygen through the PSP binder material with typical time constants ranging from 0.05 to 2.5 s. The PSP response is best characterized by a two-term exponential decay function representing a complex first-order dynamic system. In contrast, a standard pressure transducer responds as a second-order dynamic system. The two-exponential curvefit provides a convenient way to compare the time response of different PSP formulations. A mass diffusion model of the PSP response is also presented that is capable of predicting the time response of PSP layers.