Research On Vibration Of Air Conditioner Axial Flow Fan Without Volute Casing Based On One Way Fluid Structure Interaction

An axial flow fan without volute casing is widely used in the outside unit of the split-type air conditioner, and the internal flow in the axial flow fan without volute casing is much different from that in the axial flow fan with volute casing. Therefore,the improvement of the performance and stability of the fan attracts more and more attention. During the operation, the blades of the fan are simultaneously applied with coupled functions of aerodynamic force, centrifugal force and elastic force, and experimental ways are hardly used to research the effects of coupled forces on the vibration of the blade in practical work. In order to improve the vibration of the air conditioner axial flow fan without volute casing, based on one-way fluid structure interaction theory, this paper combines the numerical simulation and the experimental way to research the aerodynamic performance, structural strength and resonance of an axial flow fan, which is aimed to provide guidance for the prediction of the aerodynamic performance and resonance of the air conditioner axial flow fan. The main work in this paper is shown as follows:(1) A series of performance experiments are conducted for the axial flow fan to research on the effects of different operation conditions on the performance of the fan.Based on the Fluent to establish the calculation model, the aerodynamic performance prediction for the fan is conducted by the reference of experimental conditions. The comparison between the simulation results and the experimental results is made to validate the reliability of the simulation method.(2) Based on the ANSYS Workbench platform, by the method of one-way FSI, the aerodynamic force from Fluent results is added onto the structural model and the rotational restraint is also added to obtain the stress distribution and the deformation of the blade. The comparison of the stress distribution and the deformation under FSI andnon-FSI is made. The result shows that the largest deformation exists in the blade tip,the largest stress exists in the suction side of the leading edge of the blade root. The safety factor of the blade is far greater than the allowable safety factor.(3) Based on Bruel & Kjaer-Pulse System, the experimental modal frequency of the axial flow fan blade under the free modal is obtained and compared with calculation modal frequency based on Modal module to validate the reliability of the calculation modal. The non-FSI modal and FSI modal of the axial flow fan are also calculated and the natural frequency and modal shape of each order for three modal types above are compared with each other. The result shows that the centrifugal force and aerodynamic force can increase the natural frequency. On the basis of FSI modal, the blade resonance is analyzed to show that the fan avoids resonance. The research of one-way fluid structure interaction provides experience and guidance for the prediction of aeroelastic stability of the air conditioner axial flow fan.