Reaserch On Acoustic Radiation Of Fan Casing Under The Complex Excitation

Numerical simulation of structural acoustics is an important aspect of noise and vibration control domains.The ZR6-2X29NO.20.5F centrifugal fan is studied in this essay, simulation of the noise of the fan shell was proceeded by employing the FEM analysis and modal analysis , combining FEM and BEM.The achievements at home and abroad in noise and vibration control of centrifugal fan are reviewed firstly, which make the key problems clearer.The finite element method and the boundary element method are introduced as well as the finite element software(ANSYS and Sysnoise) .In the project,there are four parts concluded as follows:In the first part of the noise analysis and forecasting process, according to structural characteristics of centrifugal fan, the entity model and the fan shell finite element model was built in ANSYS, and then was meshed.In the second part , the finite element model of the centrifugal fan was built and the mode analysis was carried out.In ANSYS software, the first 20-order modal parameters were extracted, and the case was harmonic analysis, combining FEM and BEM, established acoustic boundary element model in ANSYS and SYSNOISE software. The sound field around the fan shell was analyzed.In the third part , the fan noise at work was carried out tests by the software LMS Testlab,getting the fan noise spectrum; the fan noise reduction was predicted by using of LMS TestLab Sound Diagnosis module for collecting real-time signal.In the fourth part , based on the previous simulation of the centrifugal fan, testing and sound diagnosis, noise reduction measures of the fan were proposed.