A sprayable fast-responding pressure-sensitive paint (fast-PSP) has been developed to measure time-resolved small pressure fluctuation on model surfaces. To realize PSP with fast response, high robustness, and high luminescence intensity, we have developed a novel ruthenium complex-based fast-PSP. The binder layers of the proposed fast-PSP were prepared by mixing room-temperature-vulcanizing silicone (silicone) and titanium dioxide (TiO ₂ ) particles with different sizes and their effects on the properties including the time response, pressure sensitivity, and luminescence intensity were investigated. The effects of the hydrophilic and hydrophobic surface treatments of TiO ₂ particle on the structure and mechanical robustness of the binder layer were also studied. The developed fast-PSP was applied to the flow field measurements behind a square cylinder and was evaluated. We have succeeded in obtaining time-series data of pressure fluctuation with high accuracy even at a mean velocity of 20 m s ⁻¹ .

We propose a noise reduction method for unsteady pressure-sensitive paint (PSP) data based on modal expansion, the coefficients of which are determined from time-series data at optimally placed points. In this study, the proper orthogonal decomposition (POD) mode calculated from the time-series PSP data is used as a modal basis. Based on the POD modes, the points that effectively represent the features of the pressure distribution are optimally placed by the sensor optimization technique. Then, the time-dependent coefficient vector of the POD modes is determined by minimizing the difference between the time-series pressure data and the reconstructed pressure at the optimal points. Here, the coefficient vector is assumed to be a sparse vector. The advantage of the proposed method is a self-contained method, while existing methods use other data, such as pressure tap data for the reduction of the noise. As a demonstration, we applied the proposed method to the PSP data measuring the Kármán vortex street behind a square cylinder. The reconstructed pressure data agreed very well with the pressures independently measured by pressure transducers. This modal-based approach will be applicable not only to PSP data but other types of experimental data.