Numerical simulation of the external acoustic field characteristics of gas pipeline leakage

The external acoustic field characteristics of leakage from pipelines are crucial in assessing the feasibility of non-contact acoustic methods for pipeline leakage detection. This study explores the characteristics of such leakage in gas pipelines by coupling Computational Fluid Dynamics (CFD) flow field calculations with the acoustic software ACTRAN. Large Eddy Simulation (LES) was first employed to calculate the unsteady flow field during a leak of gas pipelines. To account for the high Mach number associated with gas pipeline leakage, the Möhring acoustic analogy method was employed to extract the aerodynamic noise source. This approach utilized time-averaged flow velocity data from the unsteady flow field as the background flow. The study further examined the characteristics of the external leakage sound source under varying fluid pressure conditions. Additionally, the near-field and far-field propagation characteristics of the sound source were analyzed using a combination of acoustic finite element and infinite element methods. The results demonstrate that a high-velocity jet region forms at the outlet of the leakage hole during a gas pipeline leak, generating a leakage sound source predominantly characterized by a quadrupole sound source. The peak sound pressure level of the leakage noise is primarily concentrated in the low-frequency range. While the pressure differential between the inside and outside of the pipeline influences the intensity of the sound source within the jet region, it does not significantly affect the frequency characteristics of the sound source. The strong sound source distribution largely coincides with the jet region, and the propagation of the leakage sound source along the jet direction is symmetric, with this symmetry maintained across varying distances.