| As a rotating mechanical equipment,centrifugal fans have the characteristics of large air volume,stable performance and stable rotation.It is widely used in energy and power,mechanical engineering,aerospace,marine,agricultural engineering,petrochemical and HVAC industries.With the increasing requirements for the working environment and working conditions of centrifugal fans,it is particularly important to solve the noise problem of centrifugal fans,and it has become an important issue to be solved urgently in the academic and business circles.Therefore,effective and in-depth research on the vortex motion law of its internal flow field is of great significance for improving the performance of centrifugal fans and reducing noise.This paper takes a certain type of centrifugal fan as the research object,and takes the internal flow field movement law of the centrifugal fan and the effect of blade perforation on the noise of the fan as the research purpose.Aiming at the noise problem during the operation of the fan and the force and deformation of the impeller,the method of experimental aerodynamic performance and large eddy simulation was used to propose a blade perforation design plan,a centrifugal fan and an internal flow field model were established,and the internal flow field was explored Analyze the influence of blade punching position on fan noise.Mainly carried out the following research work:(1)Conduct experimental tests on the aerodynamic performance of the centrifugal fan,obtain the experimental values of the fan’s total pressure and efficiency,and establish a comparison with the total pressure and efficiency values obtained from the numerical analysis to verify the accuracy of the numerical analysis.The large eddy simulation method is used to compare with the analysis results of the RNG k-ε model;the main distribution of the internal speed and pressure of the fan at different speeds,and the deformation of the blades at different speeds are analyzed;the differences in the inside of the fan are analyzed The distribution of vorticity and velocity at time.(2)The fluid-solid coupling analysis is carried out on the centrifugal fan impeller.Based on the flow field analysis of the unsteady calculation of the fan using the large eddy simulation model,the interface between the flow field and the fan impeller is established,and the transmission of the flow field pressure data to the fan impeller is completed.The load on the impeller is mainly its own gravity,the centrifugal force generated by the rotation of the impeller and the force of the flow field on the impeller.The data results of the equivalent stress and deformation of the impeller are calculated by fluid-solid coupling.(3)A design plan for perforating centrifugal fan blades is proposed,and the influence of different perforating methods on the aerodynamic performance and noise of the centrifugal fan is studied.Broadband noise analysis of the fan is carried out,and the noise distribution on the volute and blades of the centrifugal fan at different speeds is obtained.The effect of blade perforation on the aerodynamic noise characteristics and sound pressure level of the centrifugal fan is analyzed using LES/FW-H matching technology.The results show that the surface sound pressure of the centrifugal fan structure is mainly concentrated in the collector,volute tongue and impeller;the frequency of aerodynamic noise is mainly concentrated in the fundamental frequency and octave band.The noise reduction effect of the model with the central punch design is the best;in the vertical direction,with the increase of the distance,the sound pressure level basically shows a linear attenuation trend.The results of this study provide a reference idea for the optimal design of noise reduction of centrifugal fans. |
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