共轴双桨涵道无人飞行器非定常气动特性

基于滑移网格技术和SST(shear stress transport) k -ω湍流模型,建立了模拟共轴双桨涵道无人飞行器(UAV)流场的CFD(计算流体动力学)数值方法,并通过计算风洞实验算例验证其有效性。数值模拟了共轴双桨涵道UAV在飞行过程中的动态流场,分析了涵道、飞行速度、螺旋桨转速、攻角等因素对其非定常气动特性的影响规律。计算结果表明:所建立的CFD数值计算方法适于模拟共轴双桨涵道UAV动态流场;涵道的存在显著削弱涵道螺旋桨的桨尖涡、后缘脱体涡和尾流收缩,具有较弱的桨-涡干扰和涡-涡干扰现象,明显减小共轴双桨涵道UAV的需用功率;随前飞速度增大,共轴双桨涵道UAV的升力和阻力同时增大;随螺旋桨转速增大,共轴双桨涵道UAV升力增大,而阻力减小;随攻角增大,共轴双桨涵道UAV的阻力增大,而升力先增大后减小。 

Unsteady aerodynamic characteristics of ducted coaxial propeller unmanned aerial vehicle

Based on the sliding grid technique and the SST(shear stress transport)k -ω turbulence model, a CFD(computational fluid dynamics) numerical method for the flow field of ducted coaxial propeller UAV(unmanned aerial vehicle) was established, and its effectiveness was verified by wind tunnel experiment results. The dynamic flow field of the ducted coaxial propeller UAV was numerically simulated. The influences of the factors such as duct, flight velocity, propeller speed and angle of attack on the unsteady aerodynamic characteristics of the ducted coaxial propeller UAV were analyzed. The calculation results show that the established CFD numerical method is suitable for simulating the dynamic flow field of ducted coaxial propeller UAV. The existence of duct significantly weakens the tip vortex, trailing edge vortex, propeller wake contraction, blade-vortex interaction and vortex-vortex interaction, and reduces the required power of the ducted coaxial propeller UAV. The lift and drag of the ducted coaxial propeller UAV increase as the forward velocity increases. The lift of the ducted coaxial propeller UAV increases and the drag decreases as the propeller speed increases. The drag of the ducted coaxial propeller UAV increases and the lift increases first and then decreases as the angle of attack increases.