Research On Active And Passive Combined Control Of Ventilation Pipelines Noise

Ventilation pipeline system noise is one of the main noise sources in ship cabins.Effective control of ventilation pipeline system noise is very important to improve the crew’s quality of work and life and the combat effectiveness of ships.The active and passive composite control can combine the advantages of the two control technologies to more effectively control the noise of the ventilation pipe.Aiming at the active and passive composite control of the ventilation pipes noise,the main contents of this paper are as follows:For the analysis and measurement of the noise of the ventilation pipeline.Firstly,the two main sources of the ventilation pipeline noise are determined: fan noise and pipeline air flow regeneration noise.Then,the generation mechanism of fan noise and pipeline air flow regeneration noise is explained,and the pipeline air flow regeneration noise simulation model is established to carry out the numerical simulation analysis of air flow regeneration noise.Finally,the radiated noise of the experimental ventilation pipeline was measured on site.The analysis and measurement of noise provide a basis for the selection and design of passive mufflers.Aiming at the acoustic feedback problem in the feedforward active noise system.Firstly,the mechanism of acoustic feedback’s influence on the control effect is analyzed from a theoretical perspective.Based on the theoretical analysis conclusion,the principles and advantages and disadvantages of various acoustic feedback solutions are explained.Then,the FvLMS algorithm that can compensate the acoustic feedback is used as the acoustic feedback solution,the realization process is deduced and the equation error method is introduced into the FvLMS algorithm to obtain the EEM-FvLMS algorithm.The simulation experiment compares the control line noise,broadband noise,and additional interference noise at the error sensor of the algorithm before and after adjustment,and the simulation experiment of acoustic feedback control through the measured transfer function has proved the effectiveness of EEM-FvLMS in solving acoustic feedback.Finally,a new variable step size algorithm is proposed.The simulation comparison with the existing variable step size algorithm shows that the new variable step size algorithm has smaller steady-state errors and faster convergence.Regarding the physical configuration and design of the active and passive composite muffler.Firstly,the transfer matrix method based on the plane wave theory is used to study the physical configuration of the active muffler,mainly the influence of the distance between the secondary sound source and the reference sensor on the transmission loss.Then,the physical configuration of the passive muffler was studied using the three-dimensional finite element method,including perforated tube parameters,expansion cavity parameters and sound-absorbing material parameters.Finally,according to the conclusions obtained from the study of the physical configuration of the active and passive mufflers,combined with the conclusions of the ventilation pipe noise analysis and measurement,and considering the objective factors such as processing conditions,the structure design of the active and passive composite muffler was completed and the active and passive composite muffler was processed.The active and passive composite control system for the noise of the ventilating piping is constructed by using the existing ventilating pipeline test bench and the designed and processed active and passive composite muffler.According to the determined experimental plan,the active loudspeaker noise control experiment and the active and passive composite control experiment of the ventilation pipe noise were carried out to verify the effectiveness and control effect of the control system and algorithm,and analyzed and summarized the factors affecting the experimental effect and the existing problem.