Research On Valve Active Noise Control Based On AFXLMS-CFPSO Algorithm

Regulating valve is widely used in chemical,petroleum,electric power and other industries,in the pipeline system plays an important role in opening and closing,regulating and so on.However,in the high pressure difference and unstable working condition,the throttle noise produced by the regulating valve can be close to hundreds of decibels.The high decibels noise is easy to cause people to have negative emotions such as irritability and anxiety,which seriously affects the work efficiency and physical and mental health of employees.passive noise control(PNC)and active noise control(ANC)are the two main methods of noise control.Passive noise control mainly carries out outsourcing soundproof layer treatment on the valves and pipelines that produce noise to reduce the noise.However,due to the variable frequency of noise generated in the throttling process and the long wavelength of low-frequency noise,which is not easy to be obstructed or absorbed by obstacles,passive noise reduction technology is difficult to achieve effective control of the low-frequency noise of pneumatic control valve.Active noise reduction,which is widely used today,places secondary sound sources(noise reduction sources)near the human ear to cancel the noise.This solution requires every operator in the noisy environment to wear noise reduction headphones,which cannot reduce the ambient noise from local areas in the space.Therefore,this paper proposes an active noise reduction technology scheme which integrates secondary sound source and noise source to achieve the purpose of locally reducing environmental noise in space.The main research work carried out in this paper is as follows:(1)Firstly,the intensity of noise generated by different types of valves under different inlet pressure and different opening degree was tested experimentally,and the pneumatic noise frequency of ball valve was selected for analysis.Aiming at the problem that the distribution of interna l noise sources of valve body can not be determined by experiments,the numerical simulation method is adopted to analyze the distribution of internal velocity field,pressure field and sound field of valve body,which provides a theoretical basis for the feasibility of applying active noise reduction technology to valve noise control.(2)Aiming at the problem of poor convergence speed and stability of traditional active noise control algorithm in practical engineering applications,a new filtering algorithm(AFXLMS-CFPSO algorithm)combining the compression factor particle swarm optimization algorithm with the inverse tangent function variable step size method with correction factor is proposed.Theoretical analysis shows that the new algorithm should have faster convergence rate and better steady-state error.(3)In order to further verify the stability and convergence rate of the new algorithm,numerical simulation is used to compare the noise reduction performance of the new algorithm and other tradition al algorithms.The results show that the new algorithm has a great improvement in the convergence rate,noise reduction and stability compared with the traditional algorithms.On the basis of numerical simulation,a feedforward single channel active noise reduction(ANC)system was constructed by Code composer studio software and DSPF28335 processor.The performance of the system was tested in real noise environment and the reliability of the new algorithm was further verified.(4)In order to apply the ANC system to the real valve noise environment,the distance between the noise source and secondary sound source,the radius of the noise source and the relationship between the vibration speed of the noise source and the noise reduction amount are determined through theoretical analysis,which provides theoretical guidance for the optimal placement of the secondary sound source in the ANC system.On this basis,a feedforward single channel ANC system is built to carry out active noise control for pneumatic co ntrol valve noise with different opening degrees.The experimental results show that the ANC system built with the new algorithm as the core has an average noise reduction of 19.2d B for pneumatic control valve noise with different opening degrees.