Blade Design Of Axial-flow Fan Based On Planar Cascade Design Method

Axial-flow fan is widely used in chemical industry,ships,buildings and other fields,but at the same time it is also the large energy consumer.The internal gas flow is complicated and the efficiency generally needs to be improved.Therefore,it is necessary to study design methods which is of great significance to improve fan's performance and energy allocation.Based on the original fan geometric model and numerical simulation results,this dissertation uses the planar cascade design method to optimize the rotor blade of axial fan,so that the aerodynamic performance of the fan can be promoted.In this dissertation,if the data of the chord length,the blade outlet geometry angle and the inlet flow angle at different blade's height are known,the double-arc camber lines of blade can be determined by the geometry constraint sketch.And a new axial-flow fan model can be obtained by using the 3-D geometric software to determine the section shape of different height.Then,the three-dimensional flow field numerical simulation of axial-flow fan is carried out by using CFD technology,including numerical modeling,mesh generation and independence verification,boundary condition setting,numerical calculation,post-processing of calculation results and so on.The main contents and results of this dissertation are divided into the following four aspects:(1)The influence of design deviation angle on the aerodynamic performance of axial-flow fan is studied.The results show that the proper design deviation angle can improve the efficiency and total pressure of the fan,and obviously improve the airflow.(2)The influence of the exchange of two arc positions at the geometry constraint sketch on the aerodynamic performance of axial-flow fan during continuous design is studied.In the process of the study,it is found that the fan can continue to be design by using the data of the last fan.And two geometry constraint sketches can be obtained by changing the position of two arc,denoted by method 1 and method 2.Six optimized fan models are built by collocation and combination of two different methods in the process of designing fans,and the results show that the method 2 has a better optimization effect.What's more,the efficiency and total pressure of the optimized fan have been improved at the whole flow rate condition(3)The change of aerodynamic performance of axial-flow fans with continuous design of fans is studied.The results show that within a certain range of times,the total pressure of the fan increases with the increasing number of design,but the total pressure efficiency is basically unchanged with the increasing number of design.(4)The influence of the different distribution of the outlet geometry angle on the aerodynamic performance of the axial flow fan is studied.In this dissertation,the outlet geometry angles of 6 different heights from hub to tip are chosen as design parameters to design the blade of axial flow fan impeller by orthogonal test method.The results show that the aerodynamic performance of the fan can be improved by selecting the appropriate outlet geometry angle at different height of the blade.