Theoretical And Experimental Study On Active Control Of Acoustic Radiation From Finite-length Liquid-filled Cylindrical Shell

Liquid-filled pipelines are often used to deliver fluids with a wide temperature and pressure range,but in the process of transferring energy,the liquid pressure pulsation and structural vibration of the pipe wall in the piping system,which vibrates through the entire tube system spreads downstream and eventually radiates out of the nozzle in the form of noise.Therefore,if the noise level of the nozzle is predicted in advance,it is of grate benefit to take effective and effective control measures to reduce the noise of the nozzle radiation.In this paper,the numerical control and experimental study on the active control of the acoustic radiation of the liquid filling pipe are carried out.The main work is as follows :The theoretical model of acoustic propagation of finite liquid-filled pipelines is deduced.The response of piping system is solved by traveling wave method,and the acoustic radiation of nozzle is solved.The response of the piping system is solved by traveling-wave method.The coupling between the pipe and the fluid shows the dispersion curve of the pipe system.The influence of the external fluid load on the radiant sound of the nozzle is shown as the radiation resistance.Then the influence of different excitation sources,different boundary conditions and different pipe lengths on acoustic radiation is analyzed.On the basis of the first-order shear deformation theory,the vibration differential equation of the electro-hydraulic piezoelectric cylindrical shell is deduced by the energy method,and the theoretical model of the tubular piezoelectric secondary sound source is established.On the basis of this,the natural frequency of the system is solved,and the influence of the parameters and external electric field on the sound pressure of the fluid in the tube is analyzed in detail,and the tube at different frequencies Sound pressure distribution.The active control theory analysis of the nozzle acoustic radiation is carried out by using the quadratic optimal control theory of frequency domain.The sound pressure of the downstream section of the pipe and the radial displacement of the downstream pipe wall are taken as the control target,and the sound radiation of the nozzle is taken as the evaluation point.The position of the different secondary source and the control target and the different boundary conditions of control effect,carried on the simulation analysis.At last,the sound pressure and the radial displacement distribution of the pipe are analyzed.The experimental results show that the secondary source is close to the primary source and the control target is close to the orifice,the control effect is ideal.Designed to build a tube of sound radiation active control experimental bench.The single-frequency noise at the nozzle is studied by using the notch filter and the FxLMS algorithm respectively.Then the influence of the position of the error sensor on the control effect is analyzed.Experiments show that the two control algorithms can effectively control the single frequency noise,the error sensor is far from the nozzle when the control is far better.