Study On Leakage Acoustic Source Characteristics Of Gas Pipeline

Pipeline transportation is a way of using pipes to convey gas or liquids.Compared with railway transportation, waterway transportation, highway transportation and air transportation, pipeline transportation has many advantages,such as higher efficiency, shorter construction period, lower investment, smaller occupation area,lower transportation loss,and benefits of environment protection?It has an important position in the oil, natural gas and other fluid transport. However,more than half of the oil and gas pipelines in China have entered into the middle and later stages of pipeline operation, leakage accidents occur frequently. Therefore, the real-time detection of pipeline operation and the timely detection and accurate positioning of the leakage point are of great significance to ensure the safety of oil and gas pipelines, to ensure the safety of people's lives and property, to reduce economic losses and to protect the environment.Leak detection technology for gas pipelines based on acoustic method is the use of aerodynamic noise generated when the gas pipeline leaks, to detect and locate the source of leakage. Compared with the negative pressure wave, leakage acoustic wave contains more leakage information. And compared with other leakage detection methods, the acoustic method has the advantages of high positioning accuracy, short response time, high sensitivity and strong adaptability. And the characteristics of leakage acoustic source of gas pipeline play a decisive role in the accuracy and adaptability of the leakage detection based on acoustic method. In order to investigate the characteristics of the leakage acoustic source of the gas pipeline,this paper made the simulation and the experimental research about the leakage acoustic source characteristics of the gas pipeline under different leakage aperture, different pipeline pressure, different leakage hole shapes and different leakage hole direction.It is of great significance to improve the accuracy and adaptability of leak detection technology for gas pipelines based on acoustic method and it provides a theoretical basis for the development of gas pipeline leak detection and location system based on acoustic method.Firstly, the characteristics of the leakage acoustic source of the gas pipeline are analyzed theoretically. The theory of Aerodynamic noise and the type of sound source are introduced. And the truncation error and the large eddy model used in thesimulation of gas pipeline leakage flow field are discussed. This lays the foundationfor the simulation calculation of the following chapters.Secondly, under the guidance of the theoretical analysis, the gas pipeline leakage model is established, and using this model, the flow field and acoustic sourcecharacteristics of the gas pipeline leakage are simulated. The results show that the leakage rate is linearly related to the pipeline pressure. In the vicinity of the leakage hole, there is a significant pressure pulsation,but the pressure drop area is very small,and the maximum jet velocity exceeds the .sound velocity, which belongs to supersonic flow. The leakage acoustic source of gas pipeline is broadband noise, and the lower the frequency the higher the SPL, acoustic energy is the same. The mean value of sound pressure level is increased with the increase of pipeline pressure and leakage aperture; when the hydraulic radius is the same, the mean value of the sound pressure level of the rectangular leakage hole is higher than that of the circular leakage hole, but the direction of the leakage hole has little effect on the mean value of the sound pressure level.Finally, the experimental system of the characteristics of leakage acoustic source of gas pipeline is set up, and the characteristics of leakage acoustic source of gas pipeline are studied. The experimental results demonstrate the characteristics of the leakage acoustic source obtained by simulation and this prove that the acoustic source of gas pipeline leakage is dominated by quadrupole source.