Aerodynamic Performance Calculation Of Ducted Fan And Optimization Of Duct Profile Parameters

In recent years,the vertical take-off and landing aircraft has been widely used.The rotor,as its main lifting component,has also been studied extensively.The ducted fan is a configuration of the rotor,which is particularly concerned for its safety and efficiency.The ducted fan refers to a mechanical structure in which the rotor is surrounded by a closed and suitable annular duct.In the case that the ducted fan's aerodynamic performance is greatly influenced by the duct profile,the purpose of this thesis is to optimize the profile parameters to obtain better hover performance.In order to calculate the hover performance rapidly and correctly,the 2D momentum source method is obtained.The genetic algorithm is used to optimize the parameters,in order to overcome the discontinuity and randomness of the performance-parameter function.In the case that the researches on ducted fan optimization mainly focus on the inlet radius,the duct diffuser angle,the duct diffuser length and the tip gap of blade,this thesis analyzed the duct profile in three directions.Firstly,the uncoupling of the diffuser expansion angle and the diffuser length is revealed.In Addition,the reasonable range of the diffuser expansion and the diffuser length is given under different tip gap.Secondly,the NURBS spline curve is used to generate the duct inlet profile,which give a creative conclusion about the influence of the inlet curvature radius and peak position that a smaller curvature radius and a peak more outward is preferred.Thirdly,the installation position of the fan in the duct is analyzed.When the diffuser expansion angle is 0°,and a reasonable inlet profile is adopted,the installation position has little influence on hover performance.