Study On Sound Source Location Of Internal Leakage Point And Sound Flow Solid Coupling Noise Prediction In Safety Valve

The internal leakage of the valve will seriously affect the stability of the pipeline system controlled by valve and even endanger the safe operation of the entire production device.For internal leakage of multiple safety valves and large-diameter valves placed in high-temperature,high-pressure,dangerous media or high-parameter containers,if specific leaks are not found in time for inspectio n and maintenance,it will cause casualties and economic losses.Aiming at the problem of internal leakage of the valve,the 50A47H-16 C micro-lift spring load safety valve was used as the research object to carry out the analysis of the characteristics of the aerodynamic noise source and the research of the location of the leakage point sound source during the internal leakage of the valve:(1)The background and significance of the research on valve internal leakage are introduced.The research progress and status of domestic and foreign on the acoustic fluid-solid coupling of valve internal leakage,wavelet signal analysis,denoising,and sound source positioning are studied.The necessity of the research on the characteristics of the acoustic-fluid-structure coupling,the analysis of the leakage emission signal in the safety valve,and the research on the sound source localization of multiple leak points are discussed.(2)The sound source mechanism of the internal leakage of the safety valve is analyzed.Based on the acoustic fluid-solid coupling mechanism and the Lighthill sound analogy theory,the sounds with different pressures,different apertures and different leakage forms are studied under the consideration of the dipole and quadrupole sound source models Research on the distribution of source characteristics and the law of spectrum characteristics of sound pressure level under different parameters.According to the valve internal leakage and the corresponding sound pressure level spectrum characteristics under different parameters,the quantitative study was conducted to establish a mathematical model to characterize the sound pressure level and internal leakage.(3)Aiming at the high-frequency characteristic noise signal of the internal leakage of the safety valve,the average peak and ratio(PTSR)threshold based on the average peak and ratio correction coefficient is proposed for the general threshold method of the traditional wavelet threshold denoising theory.Wavelet threshold function of elliptic curve denoising method is also proposed;The signal-to-noise ratio and root mean square error of different typical signals f or the existing threshold function and the improved threshold function are compared and analyzed.An improved wavelet threshold based on elliptic curve method combined with EMD empirical mode decomposition denoising was applied to obtain the denoising signal of leakage in the safety valve,which provided a low noise source signal for the fourth chapter of sound source localization.(4)Two widely-used sound source localization methods for time delay estimation and controllable beamforming are investigated.Aiming at the problem of large-scale energy distribution inside the safety valve,based on two localization theories,the traditional KDE algorithm is improved and analyzed,and the fusion algorithm was proposed.The traditional PHAT,KDE algorithm and self-fusion algorithm are simulated and analyzed based on the internal leakage signal of the safety valve,and the positioning recognition degree and accuracy of the three algorithms under different denoising thresholds and array element space are studied.By studying the characteristics of the aerodynamic noise source of the internal leakage of the safety valve and the location of the leakage sound source,the sound source characteristic laws at different parameters of the internal leakage of the safety valve are obtained.Based on the data fitting of a limited number of typical internal leakage parameters,the relationship between the internal leakage of the safety valve and the acoustic characteristics is obtained;at the same time,a noise reduction analysis of high-frequency internal leakage signals and a sound source localization study on multiple leakage points of safety valves are carried out,which can reduce the cost of valve inspection and maintenance,which provides a theoretical basis for studying the characteristics of the sound source of the safety valve and improving the reliability and stability of the safety valve.