| Because of the large pressure coefficient, high efficiency, small size and convenient installation, centrifugal fan is widely used in national economy and daily life. With the development of science and technology, the performance of the centrifugal fan demand is higher and higher, higher speed and higher performance is the future development direction of centrifugal fan.The aerodynamic noise of Centrifugal fan has gradually become the main factors influencing the reliability of the equipment and the comfort. Therefore, it is of great significance to reduce the aerodynamic noise of centrifugal fan at the same time to increace the flow. Based on the centrifugal fan which is used in Huawei energy-saving system,we put forward the optimization scheme by comparing simulation results with the experimental data.Specific content is as follows:(1) Centrifugal fan numerical simulation method research. Analysis of large eddy simulation, Renault average separation model and simulation of centrifugal fan flow field and the influence of sound field calculation accuracy, by comparing the experimental data for the centrifugal fan to choose the appropriate turbulence numerical simulation method; to summarize the basic equations of pneumatic acoustics, analysis of three kinds of application range of the acoustic calculation method, to choose the right for centrifugal fan aerodynamic noise calculations sound source surface and time step; through two-dimensional centrifugal fan rotating domain size effect on the simulation results of model validation, according to the actual physical environment, set up reasonable boundary conditions and solving ways.(2) The simulation of centrifugal fan and the result analysis. To introduce the geometric modeling process of centrifugal fan and study the effect of grid number on the simulation results, through the fan performance curve and P- Q wind tunnel experiment to verify the correctness of the flow field simulation; according to the sound pressure level spectrum graph and octave analysis of aerodynamic noise centrifugal fan, to study the effect of rotational speed and the change of working condition of noise characteristics and summarize main cause of pressure loss and the relationship between the vorticity and aerodynamic noise, through single blade model to analyze the causes of the blade tail edge vortex shedding.(3) The structure optimization scheme of the centrifugal fan. Guide plate and the vortex ring optimization scheme is put forward according to the location of the pressure loss generation, to explain the optimization principle of two kinds of schemes and summarize the optimization effect, we put forward ladder volute with zigzag trailing edge optimization scheme according to the distribution of vorticity, to analysis the sound pressure level spectrum diagram and suggest the noise reduction principle of optimization; we put forward the not equidistant optimization scheme according to the characteristics of the rotating noise and analyze the scope and application of scheme characteristics.(4) Centrifugal fan passive noise elimination method. To summarize the working principle of the acoustic insulation materials and design the sound-absorbing insulation type centrifugal fan according to material features; to C hoose the appropriate processing technology to manufacture of centrifugal fan and verify the optimization scheme optimization effect through the wind tunnel experiment and noise test. |
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