The Design Of A Kind Of Axial Flow Fan And The Numerical Analysis Of Its Performance Characteristics

Axial flow fan is widely used in modern society.So that the design of axial flow fan is became more and more important in modern industrial design.Traditional axial flow fan design is mainly through the method of wind tunnel experiment,which is not meet the requirements of current engineering practice due to high cost,low efficiency,and long design process.So how to design the axial flow fan economical by numerical simulation method has become the major research direction currently.In this paper,the blade design method of aerodynamic design of axial fan is introduced.A kind of axial flow turbine impeller blade and rear guide vane blade are designed by Howell cascade method.Then,the numerical simulation method of the three-dimensional flow field of the whole machine is described,including numerical modeling,meshing,boundary condition setting and convergence criterion.Finally,the full pressure and full pressure efficiency curves of the designed axial fan are obtained by using suitable modeling method and numerical simulation post-processing.At the same time,the influence of the installation angle,the rear guide vane and the number of blades on the performance of the fan is analyzed which based on the impeller designed by Howell cascade method.The conclusion is obtained through the above research.(1)The axial flow fans blade design is more consistent with the requirements by using Howell cascade method.(2)Axial flow fans blades have a greater degree of distortion by equal circulation design.The efficiency of the axial flow fans decreased significantly because that the air of outlet of the impeller has a larger circumferential kinetic energy which cannot be converted into pressure energy.The guide vane of outlet can rectify the flow field at the exit of the impeller,forcing the kinetic energy corresponding to the velocity of the air near the outlet of the impeller to be mostly converted into pressure energy,thus the efficiency of the axial fan can be improved.(3)The number of axial flow fan blades through cascade design method is fixed when established at the beginning of the design parameters.The vortex is generated by interference between adjacent blades in the cascade.Increasing the number of blades will increase the degree of mutual influence between adjacent blades,which will aggravate the vortex generation and reduce the efficiency of the axial flow fans.(4)The installation angle of the blade profile is affected by the impact angle of the inlet when the impeller speed and inlet flow rate are constant.Once the impact angle of the inlet is determined,the blade profile parameters are determined,and the dynamic characteristics of the blade profile are also determined.Arbitrarily changing the size of the installation angle of the blade profile,which changes the direction of the flow velocity at the leading edge of the blade profile,does not conform to the dynamic characteristics of the blade profile,thus affecting the overall performance of the axial flow fans,so that the efficiency is decreased.