The Fluid-Structure Coupling Analysis Of Mixed Flow Fan

As a typical impeller machine,the mixed flow fan combines the advantages of high wind pressure of centrifugal fan and larger wind flow of axial flow fan,which is widely used in industry and daily life.However,during the operation of the fan,there are various faults,such as surge,stall,noise,etc.,which will affect the stable operation of the fan.Most of these faults are caused by fluid-structure coupling,therefore the effects of fluidstructure coupling should be taken into consideration in the analysis.The dissertation mainly focuses on the deformation and damage of the impeller caused by the flow field of the mixed flow fan and the resonance phenomenon.First of all,Solidworks was used in the dissertation to carry out 3D solid modeling of a SWF type mixed flow fan,and lengthened it in the import and export position.Then it was imported into the ICEM.The whole channel was divided into four sub regions by different grid types.Then the flow state of the flow in the whole flow passage of the mixed flow fan was analyzed based on the pressure and flow velocity distribution of the whole flow passage which was obtained by numerical simulation.Secondly,the results of Fluent analysis were imported into Static Structural analysis module based on the multi physical field collaborative analysis of ANSYS Workbench,which were added to the wind turbine model solid field surface as the initial conditions.At the same time,rising rotation speed,the stress state of impeller under the fluid pressure was obtained,and then the strength of the impeller was checked.Trough the change of inlet flow rate and guide vane number,the wind pressure value and efficiency value of the fan were obtained.All the data were fitted by Matlab.Its fitted curve was studied.At last,the stress results obtained from Static Structural analysis were imported into the modal module.The modal analysis and simulation of the fan rotor was made,and the dynamic characteristics of the rotor under different conditions were obtained.By comparing and analyzing the dynamic characteristics of the rotor under different conditions,the different law of change and the influence of aerodynamic force on the rotor vibration mode were obtained.The result of fluid-structure coupling shows that the optimal guide vane number in the operation process of the fan is 15,and the optimal working condition is 6~8 m/s.The maximum total pressure is 273 Pa,and the highest efficiency is 72%.Through modal analysis,it is concluded that the effect of rotary prestress on the frequency value of the rotor is the largest,and the higher modal frequency is closer to the frequency doubling of the fundamental frequency,therefore it needs to be considered in the design optimization.