Performance And Parameter Study Of Coaxial Proprotor

This thesis designed a coaxial proprotor aircraft, a new compound high-speed rotor aircraft, which joints both the hover and vertical flight of helicopter and the high-speed performance of fix-wing aircraft. The coaxial rotors play as rotor to offer lift when in helicopter mode and tilt forward as propellers when in airplane mode. Coaxial proprotor aircrafts have lots of application both in civil and military field.Firstly, this thesis based on the blade element momentum theory(BEMT) to build the aerodynamic model of coaxial rotors in axial condition, considering the interference affects between up and low rotor. Then it used this model to calculate the lift coefficient and power coefficient and even the efficiency of the sample rotors. The effects coincided well with the experiment from wind tunnel test. It indicates that the aerodynamic model of coaxial rotors in this article can be used to investment the performance of coaxial rotors aircraft. Based on the built aerodynamic model, the thesis also developed the method to analysis the the interference aerodynamic model in transition mode, which improved the former model. Secondly, Based on the interference aerodynamic model, parameters that affect the performance of the propeller were analyzed, which include the airfoil, the blades number, the blade radius, radius ratio, the space between up and down rotor, the wash-out, the chord length, the taper ratio, the collective pitch and so forth. Then based on the results, the coaxial rotors were redesigned so that to arrive at optimal performance. Finally, this thesis discussed the differences of the aerodynamic characteristics in different mode. The manipulation pattern and control strategy are also discussed. This thesis also designed the flight control program and discussed the control system of the coaxial proprotor aircraft.