Research And Simulation On Active Noise Control Of Mine Ventilator Inlet

Fan noise is one of the hottest and most difficult topics in the field of fan research technology.The mine ventilator creates high-intensity noise during operation,which causes noise pollution to the underground,and seriously affects the physical and mental health as well as work efficiency of the workers underground.Meanwhile,the noise problem of the mine ventilator is also urgent to resolve for the performance index Factors,so the control of fan noise is of great significance.The noise mode of the fan is mainly divided into passive noise control and active noise control.It is more common to use passive noise control on the problem of fan noise reduction.However,the low-frequency noise created by the fan does not achieve the desired effect usually.Moreover,it needs to consume space to increase sound absorbing materials and increase product volume,and at the same time,it will make a certain impact on the work efficiency of the fan.Although the implementation method of the active noise reduction technology is complex,it can effectively reduce low-frequency noise and does not need to change the structure of the fan itself.Therefore,it is particularly important to design the fan equipment for active noise control.In this paper,the noise of the air inlet of the ventilator is taken as the research object,the noise characteristics of the ventilator and the main noise sources are analyzed,and the relevant acoustic theory is studied.In order to invent the active noise reduction system for the fan,the LSM is theoretically analyzed and selected to be the algorithm of the active noise reduction system,also,the hardware of the active noise control system is designed in the paper.Innovated by the idea that the noise reduction space can be simplified and segmented,three series of feed-forward active noise control units and active noise control groups are designed to control the noise at the air inlet of the fan,based on the active control model of the fan duct noise.The sound field simulation of the active noise control unit and the active noise control group designed in this paper is performed by using the acoustic simulation software Virtual.Lab Acoustics.In this process,the sound pressure distributions of the primary sound field and the sound field after noise reduction are obtained.Moreover,the feasibility of placement of the signal receiver and the secondary sound source is verified.And the simulation of the software FLUENT is used to explore the resistance of the active noise control group to the ventilation system.By the comparison and analysis of each set of active noise reduction unit and active noise reduction group in horizontal and vertical dimension,this paper shows that each set of active noise reduction unit and active noise reduction group can control the fan inlet noise to varying degrees.The signal acquisition device is placed at the digging hole on the outside of the pipe,and the noise signal can be accurately collected.The difference between the sound pressure of the noise source and the collected point does not exceed 3d B.The noise reduction efficiency of each set of active noise reduction group and unit is basically the same.Among them,the active noise reduction device of the external speaker with a diameter of 100 mm has a significant effect on the low frequency noise below 500 Hz,and the average noise reduction amount is about 13 d B.Due to the multi-pipe design of the active noise reduction group,the structure of the active noise reduction group has little effect on the wind pressure of the fan when the wind speed is less than 4m/s.Therefore,there is a certain engineering application prospect.