Aerodynamic Analysis Method And Design Optimization Of Micro-small Tilting Rotor

The micro-small tilt-rotor aircraft has the ability to take off and land vertically,hover in air,and cruise at high speeds,which can meet the needs of various flight missions.However,its working modes are quite different from those of rotors and fixed wings,which poses a severe challenge to the aerodynamic design.Therefore,it is particularly necessary to carry out research on the aerodynamic characteristics of micro-small tilting rotors,and to design efficient rotors to improve their flight performance.This paper is aimed at the fixed pitch propeller which is commonly used in micro-small tilting rotors.Firstly,an aerodynamic model based on the strip theory is built.Secondly,corresponding fast numerical calculation methods are developed.Finally,the calculation method is combined with an optimization algorithm to carry out aerodynamic optimization of the rotor shape,so that the tilting rotor has good comprehensive aerodynamic performance.The main research contents are as follows:1)An aerodynamic model of the micro-small tilting rotor is established.Based on the strip theory,the calculation method of the aerodynamic characteristics of the tilting rotor in the axial flow state and the oblique flow state is analyzed and deduced.Then the aerodynamic theoretical model applicable to the tilting rotor state is established.2)A numerical calculation method for aerodynamic performance is proposed.Based on the aerodynamic model of the tilting rotor,a fast aerodynamic analysis of the three modes of rotor,tilt,and fixed-wing cruise in the state of no-current and constant-current is made.The aerodynamic performance of the rotor during the tilting transition is mainly analyzed.3)A set of rotor aerodynamic characteristic test device was designed and built to test the thrust and torque of the tilt rotor in rotor mode,tilt motion mode,and fixed-wing cruise mode to verify the accuracy of the calculation method.4)An aerodynamic optimization method for micro-small tilting rotor is proposed.Firstly,a mathematical model for aerodynamic optimization of the tilting rotor is established.Then the NSGA-?algorithm is used to solve the problem of maximizing the hovering efficiency and cruising efficiency of the tilting rotor.Finally,the rotor geometry can be obtained when the comprehensive performance is optimal.