| In the process of exploitation of a gas field in Sichuan,there is a serious problem of excessive noise which is up to 110dB,far exceeding the national standard of noise emissions.High noise environment not only affects the normal work of workers around the well site,but also causes serious harm to production safety.It is not only of great theoretical and practical significance,but also has obvious economic and social benefits to study the noise of the well site.The object of this paper field is the wellhead throttle pipe.Through the numerical simulation analysis of aerodynamic noise and the acoustic vibration coupling of gas,this paper are studied on the effects of different structures and different operating conditions on the aerodynamic noise and the acoustic radiation of the throttle pipe.And then based on this basis,a reasonable and effective noise reduction scheme is proposed which is applied to the scene made a noise reduction effect.This paper mainly carry out research work from the following aspects:(1)The aerodynamic noise is generated in the bend pipe and variable diameter pipe.Based on the combination of the large eddy simulation and Lighthill acoustic analogy,the mechanism of the aerodynamic noise is analyzed.The main reason of the aerodynamic noise in the elbow is the existence of the two flow and the vortex,and the main reason of the noise in the variable diameter pipe is the vortex.And the aerodynamic noise of the bend pipe and variable diameter tube is a kind of wide band noise which has no obvious main frequency and has sound energy at many frequencies(2)the structure and operating conditions affect the aerodynamic noise.Through the analysis of bend radius,bend angle and bending conditions on the aerodynamic noise influence,we can be increased that the bending radius and bending angle decreases which can reduce the aerodynamic noise value.When bend radius increased from R=D to R=3D,the maximum sound pressure level decreased by 8.98dB.When the bending angle increases from 90 degrees to 150 degrees,the maximum sound pressure level decreased by 4.79dB.The influence of internal pressure on aerodynamic noise is small,but the influence of speed on the sound pressure level is larger in the elbow.We can control the noise by reducing the flow rate in the pipe,the flow rate in the pipe should be reduced below 10m/s.According to the analysis of the aerodynamic noise of the variable diameter pipe,it can be obtained that reducing the noise by reducing the tapered angle.(3)Study on acoustic radiation law of aerodynamic noise in throttle pipe.Through the establishment of pipeline internal cavity-pipe wall structure-external acoustic coupling model,we can be obtained that the acoustic resonance of pipeline in the vicinity of 117Hz under the excitation of acoustic loads.The tube wall thickness increased 1mm,the maximum amplitude averagely decreased about 0.02mm,the maximum sound pressure level decreases 6.7dB,average sound pressure level decreases 5.07dB,the maximum sound radiation power level decreases 7.54dB,the average sound radiation power level decreases 6.3 ldB.The bending radius increased 0.5D,the maximum amplitude averagely decreased about 0.02mm,the maximum sound pressure level decreases 7.94dB,average sound pressure level decreases 5.97dB,the maximum sound radiation power level decreases 8.30dB,the average sound radiation power level decreases 6.70dB.The increase of pipe constraint can improve the rigidity of the pipeline,reduce the vibration displacement of the pipeline,and reduce the noise radiation.(4)Combined with the research contents of the third chapter and the fourth chapter,the paper puts forward the noise reduction scheme and applies it to the scene.Aiming at the well site,the paper puts forward two kinds of noise reduction schemes,which are active noise reduction and passive noise reduction.Two schemes used in the gas field which made a good noise reduction effect.It verified the feasibility of the scheme. |
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