Denoising pressure-sensitive paint measurements to detect sub-Pascal surface pressure fluctuations associated with aeroacoustic tones

Pressure-sensitive paint (PSP) measurements were denoised using projected multivariate singular spectrum analysis (PMSSA) to extract sub-Pascal surface pressure fluctuations. Combined with coherent output power (COP) analysis, the method reduced the noise floor by more than an order of magnitude, enabling resolution as low as 0.1 Pa ² /Hz. Application to a two-dimensional NACA 0012 airfoil reveals coherent surface-pressure structures associated with tonal trailing-edge noises, including a secondary component that is not an integer multiple of the primary tone at a Reynolds number of 3.5× 10⁵ . A two-dimensional mid-chord structure on the suction side overlaps with that of the primary tone and is consistent with a laminar separation bubble. Quantitatively, the COP obtained from PSP data processed with PMSSA was lower than that from the pressure transducer, indicating partial attenuation of trailing-edge noise components.