Analysis And Control Of Aerodynamic Noise Of A Light Commercial Compressor

With the improvement of people’s living standards,refrigeration products are indispensable in life.Reducing the noise of the product is of great significance to improve people’s living and working environment.Aiming at the problem of vibration and noise of a light commercial compressor,this paper studies the influence of the intake and exhaust structure of the compressor on the aerodynamic noise,which provides reference for improving the comprehensive performance of refrigeration products.Firstly,on the basis of analyzing the development status and noise control technology of light commercial compressor,the whole machine noise test and spectrum analysis under various working conditions are carried out.The tests include a standard working condition test of the compressor,a removing pneumatic parts test of the compressor,a removing pneumatic and moving parts test of the compressor,a removing suction muffler test of the compressor,and a removing inner exhaust pipe condition test of the compressor.The results show that the aerodynamic noise is the main noise source distributed in 160～12500Hz,followed by the mechanical noise distributed in 630～4000Hz.Electromagnetic noise has less influence on the noise of the whole machine,and the intake noise is stronger than the exhaust noise.Secondly,according to the results of noise test analysis,the basic theory of compressor pipeline sound transmission,the principle,classification,use environment and adaptive frequency band range of common muffler are comprehensively described.At the same time,the evaluation indexes of muffler acoustic performance and aerodynamic performance,and the common analysis methods of muffler performance are described in detail.Thirdly,on the basis of theory and experiment,the improvement measures are put forward.The transfer matrix equation of inner exhaust pipe muffler is established by using the four-terminal network method,and verified by finite element method.The structural parameters of inner exhaust pipe muffler are analyzed by using the transfer matrix method.The structure parameters of inner exhaust pipe muffler are optimized by genetic algorithm in Matlab software.This optimization process takes the muffler transfer matrix as the objective function,the maximum average transfer loss value of 1500～2600Hz as the optimization target,the spatial structure as the constraint condition,and the internal structure parameters of the muffler as the optimization variable to solve.The improved transmission loss of the muffler is improved within 1500～4000 Hz,and the average transmission loss is changed from 34.8dB before optimization to 55.4dB after optimization,and the noise reduction effect is obvious.The design of the new internal exhaust pipe processing production and installation test,and the standard condition noise value to compare,the whole machine sound power level reduction of 1.83dB(A),the average cooling capacity reduced 4W corresponding to the COP value reduced by 0.01,the performance loss of 0.73%,the new internal exhaust pipe noise reduction effect is good,refrigeration performance has little impact.Finally,in order to reduce the aerodynamic noise at the suction end,the external structure parameters of the suction muffler are optimized according to the muffler acoustics theory.The numerical analysis and performance optimization of the suction muffler are carried out.The acoustic and resistance performance of the muffler structure were analyzed by using the software Lms Virtual.Lab and Fluent respectively.According to the suction end to improve the frequency band 600～1200Hz,determine the new suction muffler scheme.In order to prevent the resonant noise of structure and gas column,the modal analysis of suction muffler is carried out.The new suction muffler 3D printing and prototype test,compared with the standard condition noise value,the acoustic power level reduced 2.87dB(A),accounting for 5.1%of the whole machine-noise,noise reduction effect is more obvious.Cooling capacity reduced 13 W corresponding to the COP value reduced by 0.02,performance loss of 1.5%,less than 5%design value,to meet the supporting commercial super food cabinet equipment refrigeration capacity needs,but the structural design still needs to be further optimized.