Research On Reducing Noise Of The Outdoor Unit For Air Conditioner

With the development of the life, the air conditioner is used widely. Meanwhile the customers are eagle for the quiet ones and the noise lever has been an important target to evaluate the quality of an air conditioner.In the thesis, noise radiated from the outdoor unit of split type room air conditioners was tested and investigated. The source of the noise was identified. The theory of noise generation was introduced and the peak noise frequency was calculated. The tested peak frequency was compared with the calculated peak frequency; they agreed each other very well. This proved that the testing result is reasonable. The conclusions of the noise reduction of the outdoor unit are as follows: (1) the reduction of the discrete noise from the fan; (2) the reduction of the vibration of the compressor's shell.The theory the wide band noise of the fan and the compressor noise such as shell vibration noise, aeroacoustic noise, mechanical noise and electromagnetic noise are also discussed carefully.The finite element model of the compressor's shell was founded. The calculated modal of the shell was obtained through the ANSYS software. The advantage and disadvantage of the three calculated methods of viscoelastic structure which were used in engineering were compared. An advanced calculated method of viscoelastic structure was put forward. In this method the elastic modulus and loss factor of the damping material with frequency change were considered, thus improve the calculation accuracy. At last, the location of the damping on the shell was optimized based on advanced modal strain energy forward in this thesis.