Study on internal leakage vibration and noise characteristics of spring-loaded full-opening safety valve

After long-term operation, the valve seat sealing surface of a safety valve is prone to erosion and wear, resulting in internal leakage and inducing vibration noise. Addressing the lack of acoustic mechanism theoretical support in existing internal leakage detection methods based on acoustic emission signals, this paper takes a DN (nominal diameter) 100 PN (nominal pressure) 25 spring-loaded full-lift safety valve as the research object, establishing typical internal leakage channel models of semi-circular and rectangular shapes. A hybrid acoustic–fluid–structure interaction method combining large eddy simulation and Ffowcs Williams–Hawkings is employed to study the vibration noise characteristics under different internal leakage forms. Results show that the internal leakage vibration radiation noise is mainly concentrated in the 13–17 kHz frequency band, with sound pressure pulsation peaks of approximately 85–95 dB, and irregular sound field directivity in the high-frequency band. Under the same leakage cross-sectional area, the peak frequency of the rectangular channel is higher than that of the semi-circular channel; as the cross-sectional area and number of internal leakage channels decrease, the total sound pressure level decreases while the peak frequency increases. Experimental and numerical results show good consistency in terms of dominant frequency distribution and frequency band characteristics, verifying the effectiveness of the numerical method presented in this paper. This research can provide a theoretical basis for monitoring internal leakage noise and diagnosing sealing surface damage in safety valves.