Research On Aerodynamic Noise Characteristics And Noise Reduction Of RTJ-50/4.0ZL Gas Pressure Regulator

Axial flow regulators are commonly used in pressure regulating environment with high pressure difference and velocity.In addition,aerodynamic noise is easily produced by the excessive shear force between the fluid inside the fluid.Thus,the axial flow regulator is accompanied by more serious noise pollution while regulating the pressure stability.The theory research of axial voltage regulator for noise reduction is relatively mature,but the engineering applications is relatively lagging.The general noise reduction method is to cut off the sound propagation path and construct various acoustic enclosure structures.However,the actual noise reduction effect is not significant.The paper selects the RTJ-50/4.0 ZL axial flow regulator as the object of study.The axial flow regulator is developed and performed numerical simulation based on the acoustic analogy of FW-H equation and acoustic boundary element theory.The simulation results are compared with the experiment data to validate the accuracy of the model.In addition,the flow and acoustic field of axial flow regulator are studied to investigate the effect of flow field on the sound field.The mechanism and characteristics of aerodynamic noise generation for the related axial flow regulator with the same series of RTJ-50/4.0ZL axial flow regulator are explored.Using the holes jet muffler for noise reduction processing,and provide the reference for engineering applications about the noise reduction technology.The research contents are as follows:(1)In the paper,according to the CAD design drawings,the numerical model is developed for RTJ-50/4.0 ZL axial flow regulator based on the acoustic analogy of FW-H equation and acoustic boundary element theory.In addition,the internal flow channel is extracted to perform acoustic simulation.Furthermore,the simulation results are compared with the experiment data to validate the accuracy of the model.The pressure filed,velocity field and vorticity strength of internal flow channel are analyzed from steady state and transient simulation.The steady state simulation results are compared with the transient simulation results,and thus the transient simulation is chosen as flow filed analysis.Through the study of flow field,on the one hand,finding the noise source and studying the influence of the flow stress for the sound source.On the other hand,the study of flow field characteristics provide theoretical support for the sound field.(2)Firstly,the paper is based on the theoretical analysis of acoustics basic equations to study the source types,the near and far field types about RTJ-50/4.0 ZL axial flow regulator.Based on the FW-H equation acoustic analogy method,the sound field is researched,and thus the acoustic analogy method is chosen to analyze the aerodynamic noise characteristics.The flow noise spectrum,directivity,location,and impact factors are investigated.The results show that the pneumatic noise is high frequency noise and the acoustic energy concentrates on the high frequency region.The sound source type is the dipole source.The noise area of the axial flow regulator is composed of upstream and downstream pipe area and the valve cavity area,and flow noise is most obvious at the downstream pipe area.The effects of the pressure and velocity on the aerodynamic noise of axial flow regulator are analyzed,combining with analysis to prediction of the flow field influence,then through the acoustic simulation to verify the prediction.The results show that the excessive pressure difference is the main reason for flow noise.Therefore,if the pressure difference is too large in the actual voltage regulation,the method of regulating step by step is adopted to noise reduction,which will effectively reduce the aerodynamic noise.(3)For the high aerodynamic noise problem in the RTJ-50/4.0 ZL axial flow regulator,this paper put forward a noise reduction method,this text selects the silencing technology in passive noise reduction method.Contrasting the noise reduction effect of micro perforated plate muffler and hole jet muffler.The hole jet muffler is more suitable for axial gas regulator.According to the formula design and engineering experience,the muffler parameters are as follows:the pore diameter is 3 mm,the hole spacing is 15 mm,the muffler pipe is 400mm,the muffler pipe diameter is 36mm,there are altogether 336 number of holes,the total area of holes is 2.37 × 10-3 m2.Installing holes jet muffler in the downstream piping where the aerodynamic noise problem is the most serious.The results show that the hole jet muffler can effectively reduce the overall noise of the axial flow regulator.It decreased the total sound pressure level from 110 dB to 80 dB.