Measuring tiny pressure fluctuations using fast pressure-sensitive paint and phase-lock technology: Uniformity evaluation of resonance tube

The tiny pressure fluctuations across the end wall of the resonance tube at different frequencies were captured using fast pressure-sensitive paint (fast PSP) and the phase-lock method. The high signal-to-noise ratio images of phase-averaged pressure fields (57.85 dB at 9076Hz) were obtained by repeatedly recording the pressure data at specific phases. A method reducing the measurement errors caused by illumination fluctuation and photodegradation of PSP was proposed and demonstrated. Afterward, the pressure distributions at different phases in acoustic fields with different resonance frequencies were measured. The measurement errors were reduced by a newly proposed photodegradation correction. The pressure distributions were further corrected based on the dynamic calibration results, i.e. phase delay and gain attenuation. The pressure fluctuations measured by the PSPs corresponded to those determined by a pressure transducer, and the transient pressure distributions across the cross section within the range of 10 kHz was proven to be uniform. • Pressure uniformity on the end wall of the acoustic resonance tube is evaluated. • High signal-to-noise ratio pressure fluctuations are captured. • A method to reduce errors caused by photodegradation and irradiation fluctuations is proposed. • Corrections of response delay of PSP at high frequencies are performed.