Research On Noise Reduction And Vibration Reduction Technology Of Bionic Coupling Contra-rotating Fan

As a local ventilation equipment of the mine mining face,the contra-rotating auxiliary fan for mining play an important role in mine ventilation system.Noise and vibration is an important measure index for measuring the performance of contra-rotating fan.Due to the long-term operation of the contra-rotating fan in the harsh environment of the coal mine and the unsteady aerodynamic force between the impellers,the noise and the vibration are intensified,which seriously affects the health and safety of the workers on-site.Therefore,the aerodynamic noise and vibration of the contra-rotating fan are analyzed,which has practical application value and significance for noise reduction and vibration damping of the contra-rotating fan.Acontra-rotating fan is designed through aerodynamic theory,and analyzed the flow field and noise of the fan under different working conditions has analyzed by means of finite element analysis software;the flow field and noise distribution law of the contra-rotating fan in several different conditions was obtained,and the noise spectrum curve of the sound power level distribution cloud map and monitoring point of the complete blower was obtained also.The main noise sources were found by RMS image.It can be shown that rotational noise and eddy noise were the main factors affecting the contra-rotating fan.The vibration frequency and vibration displacement of the contra-rotating fan are analyzed by the finite element analysis method.The surface parameters of parrot wing feathers were extracted through experiments,and the bionic coupling design of contra-rotating fan blades was carried out according to the bionics principle.Five bionic schemes were determined.The flow field and noise of the five design schemes were analyzed with the finite element method,and the flow field and noise of the bionic model and the original model were compared.It is shown that different degrees of noise reduction effect are obtained,the effect of noise reduction for the medium-high frequency is significantly,blade tip front zigzag structure can effectively reduce the blade tip vortex noise,reduce the blade tip discharge caused by the broadband noise,blade trailing edge sawtooth structure can effectively delay the trailing vortex shedding,reduce the aerodynamic noise of the fan and blade pressure side rib structure can effectively reduce the suction surface and pressure surface pressure gradient,reduce noise.As the combination of blade trailing edge sawtooth and rib on pressure surface has better noise reduction effect,the bionic coupling structure is designed as rib with equal distance distribution on the pressure surface of the contra-rotating fan blade,and the rib trend is consistent with the blade tip line,showing a ring arrangement,and the blade trailing edge is designed as a sawtooth shape.Orthogonal regression experiment is designed for noise test of contra-rotating fan,the relationship between the A-weighted sound pressure level and rib widths,rib spacing and trailing edge blade sawtooth width is established.The results show that the rib structure and sawtooth structure of fan can reduce noise dB,but the rib structure for the noise reduction is significant,and the noise reduction effect is best for the rib spacing 15 mm,rib width 3.6 mm,trailing edge sawtooth width 3.2 mm,the noise reduction effect is best.The vibration performance of the bionic fan under free modal,centrifugal force and fluid-solid coupling is studied.Compared with the original fan,the vibration frequency and vibration displacement of the bionic impeller are reduced.The surface deformation and stress of the blade are reduced,and there is a certain weakens the vibration.According to the principles of aerodynamics and bionics,this paper designed the bionic coupling pair of the contra-rotating fan,and studied the noise reduction and vibration reduction technology of the contra-rotating fan by means of the finite element analysis software and the orthogonal regression experiment of noise test.This research result is of great significance to reduce the noise and vibration of cyclone in underground coal mine and has wide application prospect.