Numerical Simulation Of Flow Field And Acoustic Field Of Pipeline Micro Leakage

Pipeline leakage is a serious threat to the safety and economy of pipeline transportion.In order to study the micro leakage detection technology of the gas pipeline,test the micro leakage of pipeline timely,prevent leakage diameter changes and cause accident,so there is a numerical simulation to study the distribution of flow field,sound and acoustic field when the pipeline leaks.This paper calculates respectively the flow field distribution of different shapes,different leakage diameters and different working conditions firstly,which is based on the computational fluid dynamics theory,and analysis the flow field characteristics,such as flow velocity,pressure and mass flow rate.According to the actual pipeline parameter,a micro leakage test bench is established,and the experiments are carried out to verify the numerical simulation method.Secondly,the flow field calculation results will be imported the broadband source model and the Ffowcs Williams&Hawkings equation model,and calculate the source characteristics and the acoustic field distribution.Then,when the pipeline annulus mediums are air and water and drivepipe leaks,distribution of the flow field and acoustic field are simulated and analyzed,and it is concluded that the flow velocity,pressure,sound power level,acoustic frequency spectrum and volume fraction within the leakage orifice and pipeline annulu.The results show that the numerical simulation model are suitable for simulating the micro leakage of pipeline.The larger the section of a leakage orifice is,the closer the leakage orifice shape is to circle,then the faster the gas pressure drops along the leakage orifice,the higher the gas flow velocity,the sound power level and sound pressure are,and the maximum of the sound power level is at the joint of the main pipe and the leakage orifice.The main sound source of the micro leakage is the dipole source with little effect by the internal pressure of the pipeline,which mainly affects the quadrupole sound source,and the smaller the diameter of the leakage orifice,the more significant effect of pressure on the sound power level is.Compared with water,the annular medium is air,the flow velocity is bigger,the gas flow is more stable after the leakage orifice,and the range of sound power level is bigger,the sound pressure level of the reference point is bigger in the high frequency part.When the drivepipe leaks,the sound pressure level of the pipeline is obviously reduced.Therefore,the numerical simulation method of this paper can be used to calculate the pipeline micro leakage,and the research on the detection equipment can consult the distribution of the leakage flow field,sound source and acoustic field.