Application Research On Noise Reduction Of Side Channel Blower Based On Phononic Crystal

Personnel factor is one of the main causes of safety accidents.When workers work in industrial production-manufacturing places where noise exceeds the standard for a long time,it will not only causes health problems,psychological and physiological changes,thus resulting in unsafe human behavior.Higher environmental noise can also cover up the warning signs of accidents and dangerous alarm signals,so that operators can not hear the alarm signals.So solving the problem of noise has become one of the keys to safe production.In this paper,a phononic crystal acoustic shield of a side channel blower is proposed to propagate path of radiated noise.The noise reduction and heat dissipation characteristics of the phononic crystal acoustic shield are evaluated by combining experimental research and numerical simulation.The main contents and conclusions of this paper are as follows:(1)The nine-point measurement method and near-field acoustic pressure front method are used to measure and analyze the noise value and spectrum characteristics.The test results show that the overall sound pressure level of the side channel blower is 84.2dB(A)under the calibration condition,which exceeds the standard 14.2dB(A).And the target noise reduction is15 dB(A).Through the spectrum analysis and data processing,it is concluded that the radiated noise of the side channel blower is the largest in the low frequency band of 200 Hz~315Hz and the medium and high frequency band of 1250 Hz~2000 Hz,especially in the frequency bands with 251 Hz and 1581 Hz as the center frequency.The main noise sources of the studied side channel blower are determined to be the pump side and the drive motor side.(2)The energy band characteristics of phononic crystal cells are calculated by Comsol Multiphysics and the existence of band gap is verified.The results show that the outwardly convex locally resonant phononic crystal plates have excellent sound insulation effect in the whole frequency band,and will not affect other frequency bands.By changing the material parameters,it can be obtained the influence of the elastic modulus and density of the cladding layer composite plates composed of different matrix materials and oscillator materials on the band gap of external convex phononic crystals.By changing the structural parameters,it can be obtained the influence of the cladding layer thickness and oscillator thickness,the thickness of matrix materials,the cross-section size of components and the cavity structure onthe band gap of external convex phononic crystals.This paper chooses steel with 3mm thickness as the base material and 50 mm lattice constant,lead cylinder with 2mm thickness and 5mm radius as the oscillator material,silicone rubber with 10 mm thickness,10 mm outer diameter and 6mm inner diameter as the cladding material.(3)According to the working principle of side channel blower,the acoustic shield of the side channel blower based on phononic crystal is designed,and the simulation calculation of the sound insulation and heat dissipation performance is carried out.Virtual Lab Acoustics is used to analyze the sound insulation performance.It is concluded that the phononic crystal sound insulation cover has band gap characteristics at 200 Hz~350 Hz band and two peak values at1500 Hz~2250 Hz band are 40 dB(A).The average sound insulation capacity of the phononic crystal sound insulation cover is 22.1 dB(A)by simulation calculation,but the noise leakage at the ventilation louver is serious.The U-shaped baffle ventilation structure was used for the retrofit.The average sound insulation capacity of the retrofitted baffle was 24.8dB(A),which was 12.2% higher than that before the improvement.The flow field characteristics of the sound insulation hood were analyzed by Fluent,which proved that the designed sound insulation cover met the requirements in both noise reduction and heat dissipation.(4)In strict accordance with the simulation and optimization parameters,a convex local resonance phononic crystal acoustic shield was fabricated,and the actual noise reduction effect was compared with the traditional one.The experimental results show that the insertion loss of the traditional optical plate sound insulation cover is 13.9 dB(A),which does not reach the target noise reduction of 15 dB(A).And the noise reduction effect at low frequency is not ideal.The insertion loss of the phononic crystal sound insulation cover is 18.6 dB(A),which meets the target noise reduction.The noise reduction performance is improved by33.8% compared with the traditional one.The noise at low frequency band is effectively reduced,especially at 251 Hz,the radiation of the fan is reduced.The peak emission noise is reduced from 87 dB(A)to 52.1 dB(A),which verifies the low-frequency noise reduction characteristics of phononic crystal sound insulation cover.