Research On The Influence Of Collocation Of Rotor-Stator Blades Of Axial Flow Fan On Aerodynamic Noise

Nowadays, in the case that electronic devices are increasingly miniaturized and integrated, small axial cooling fans are widely used in electronic products because of its characteristics of large ventilation volume, small size, easy installation and low costs. At the same time, the increase of fan aerodynamic noise has become an acute problem. Rotor-stator interaction noise is an important part of axial cooling fan aerodynamic noise. It is very significant to make the research on the impact of the collocation of rotor-stator blades number, setting angle and the axial spacing on the aerodynamic noise. In this paper, an axial flow fan is used as the research object. Using numerical simulation method, combined with the experimental verification, the influence of the collocation of rotor-stator blades on aerodynamic noise is researched, and the law of the influence on aerodynamic noise of the three collocation mentioned above is concluded. The specific contents are as follows:(1) Research on the numerical simulation method of rotating impeller aerodynamic noise. Through numerical simulation on a simple two-dimensional rotating impeller, analyze the factors influencing the accuracy of rotating impeller flow field and sound field simulation, such as Large Eddy Simulation and Detached Eddy Simulation, dynamic mesh model and dynamic reference frame model, the computational domain boundary layer mesh size and the like, and the appropriate fan turbulence model and mesh type for the numerical simulation is selected.(2) Research on the effect of the axial spacing of rotor-stator cascade on aerodynamic noise. Enlarge the axial spacing on the basis of the original model, simulating the flow field and the sound field, analyzing the effect of increasing the axial spacing on fan flow field. By combining the contour of the flow field parameters and SPL spectrum, a reasonable explanation and instructions are made on the sound pressure level of the final results. What’s more, the experiments is carried on to verify the correctness of the simulation methods of the two fans flow field and sound field.(3) Research on the effect of the number of rotor-stator blades on aerodynamic noise. On the basis of the original axial cooling fan, 10 simulation models of different number of rotor and stator blades are obtained by changing the number of rotor blades and the stator blades. Using the correct and feasible numerical simulation method which has been verified by the experiments, the 10 groups of fan models mentioned above is simulated, and the results of sound field of the fans are obtained, and the law of the influence of the number of blades on the aerodynamic noise is summarized.(4) Research on the effect of the setting angle of blades on aerodynamic noise. By changing the fan blade setting angle, 3 fan models with different blade setting angles are obtained. By calculating and analyzing fan flow field and the sound field with the same numerical method, the law of the influence of the different setting angles on the fan flow field and the aerodynamic noise is summed up.