Aerodynamic Layout Design Research Of A Tandem Twin-Rotor Unmanned Helicopter

Compared with single-rotor helicopters,the tandem twin-rotor helicopters have a special arrangement of the front and rear rotors that cancel each other out of the anti-torque effect.The arrangement of the front and rear rotors also causes complex aerodynamic interference problems of the double rotor/body.In this paper,for the tandem twin-rotor unmanned helicopter,the aerodynamic characteristics of the tandem fuselage are first studied,and the drag reduction analysis is completed.Then,the flight dynamics modeling of the tandem twin-rotor unmanned helicopter is carried out and the trimming calculation is performed.Finally,The aerodynamic flow field characteristics of the tandem double rotor/body in hovering and forward flight conditions are analyzed.The effects of the longitudinal and vertical spacing of the front and rear rotors on the aerodynamic performance of the double rotor are studied.The specific research contents of this paper are as follows:In this paper,the aerodynamic characteristics of the tandem fuselage flow field are first analyzed,and the drag reduction of the fuselage is completed for two factors: the fuselage head and the power cabin.Then,according to the maneuvering characteristics of the tandem helicopter,the flight dynamics modeling of the tandem unmanned helicopter is carried out.In the aerodynamic modeling of the rotor,the interference between the inflow ratios of the front and rear rotors is considered.The impact on rotor aerodynamics.In the aerodynamic modeling of the fuselage,the parameters such as the lift resistance of the fuselage calculated in the first chapter are introduced.Establish a balance equation of the tandem helicopter and complete the balance calculation.Finally,using the momentum source method to simulate the flow field of the tandem double rotor/body in the trim state,the pressure distribution and the axis of the tandem double rotor/body flow field in the hover state and the forward fly state are studied respectively.To the velocity distribution,analyze the aerodynamic interference between the two rotors and the aerodynamic interference between the double rotor and the fuselage.As the longitudinal and vertical spacing of the front and rear rotors increases,the tension coefficient and power factor of the dual rotors also increase.Therefore,in order to obtain better aerodynamic performance,it is necessary to increase the longitudinal spacing and vertical spacing of the front and rear rotors as much as possible.