Resonance characteristics and correction of pinhole and open-cavity mountings in wall pressure fluctuation measurements

Recessed mounting is a common technique for measuring wall pressure fluctuations in turbulent boundary layers. However, cavity resonance can severely distort the measured signal, so correction is required. This study investigates the resonance characteristics of pinhole and open-cavity recessed mountings through wind-tunnel experiments. Two distinct resonance mechanisms are identified. The open-cavity mounting behaves mainly as a standing-wave system controlled by the cavity geometry. By contrast, adding a pinhole cover turns the system into a high Q Helmholtz resonator and increases the resonance peak by 25–30 dB. To reduce these distortions, a single-resonator correction model is developed for the pinhole mounting. For the more complex open-cavity configuration, a Multi-Peak Envelope (MPE) correction model is proposed. Validation results show that both models effectively remove resonance-induced contamination from the spectra. The corrected data for the pinhole mountings agree well with the Goody theoretical model. This work clarifies the flow–acoustic coupling in recessed mountings and provides validated spectral correction tools for accurate high-frequency broadband measurements of turbulent pressure fluctuations.