Study On Aerodynamic Characteristic And Shape Parameters Optimization Of Scissors Ducted Rotor System

The results show that the scissors rotor and the ducted rotor have better aerodynamic characteristics,it is widely used in helicopter tail rotor,UAV main rotor and other scenarios.This paper established a special configuration: scissors ducted rotor system with scissors rotor embedded within the duct,for use as the main rotor of aircraft and other scenarios.In this paper,the aerodynamic characteristics of scissors ducted rotor system are studied with CFD.First,this paper introduces the research background,purpose and significance of the subject,as well as the current research status of domestic and foreign.Because the research in this paper is still in the early stage there is limited research on domestic and foreign research with regards to the aerodynamic characteristics of ducted rotor(propeller)and scissors rotor(propeller).Considering the calculation accuracy and efficiency,based on CFD commercial software Fluent,combined with study in this paper,the following numerical calculation method is set up: selected MRF model which is suitable for hovering state calculation.Second order upwind scheme is used to discretize the viscous N-S equation on unstructured grids,and SIMPLE algorithm is used to solve the discrete governing equations.A two-equation eddy viscosity model SST K-ω with Reynolds average method is used to address the turbulence problems.A comparison with NASA wind tunnel experiment data is made to verify the accuracy of the calculation method.The effected on aerodynamic characteristics of system were studied based on the selected CFD numerical calculation method with 8 geometric parameters: the tip clearance between rotor and duct,the cone Angle of duct,the ratio of duct height to diameter,the scissors angle,the axial relative position between the disc and duct,the axial distance between upper and lower rotors,the swept angle of blade tip,and the number of blades.The effect of rotating speed on aerodynamic characteristics of system were studied.The inner mechanism of the change of aerodynamic characteristics was studied,some meaningful conclusions are obtained,aim to provide reference for geometric design of scissors ducted rotor system.These calculations are used to optimize the geometric parameters of the scissors ducted rotor system.Calculated and analyzed the aerodynamic characteristics of the optimized configuration,aerodynamic characteristics are compared with those of the same scale scissors rotor.The aerodynamic characteristics of the optimized configuration have been improved.