垂直起降无人机涵道螺旋桨系统特性及计算方法研究

Research on the Characteristics and Computational Methods of Ducted Fan System of VTOL UAV

涵道风扇垂直起降无人机不同设计阶段对升力系统特性的精度要求也不同。为寻求具有一定可信度的涵道螺旋桨特性不同计算方法,在螺旋桨动量理论的基础上,通过引入轴向功率系数,建立了考虑气流旋向运动的涵道螺旋桨动量理论模型。分析了拉力比例因子等参数对升力系统总体特性的影响。在研究翼型大迎角特性的基础上,建立了以诱导速度为求解参数的涵道螺旋桨修正动量—叶素理论模型。基于非重合滑移网格技术,通过求解旋转参考坐标系下的N-S方程,进行了涵道螺旋桨非定常数值模拟。计算结果表明,基于修正后的动量-叶素理论计算结果更接近真实情况。在总体设计阶段可以提供具有一定可信度的涵道螺旋桨基本特性。数值模拟结果和试验结果较吻合,可以为详细设计阶段提供计算依据。

The precision requirement of lifting system is different in different designing phases for VTOL UAV of ducted fan. Based on the momentum theory of propeller, the ducted propeller model is proposed by using axial power coefficient, considering the rotation motion of airflow. The effect of some parameter such as drag proportion factor of duct on the overall characteristics of lifting system is analyzed. By applying the modified momentum-profile theory, the model of ducted propeller with aerofoil of large angle of attack is proposed. The induced velocity is re- garded as variable of this model. By solving the Navier-Stokes equation in the rotation reference frame and applying the sliding mesh method of multi-block mixture grid, the unsteady numerical simulation of ducted propeller is con- ducted. The result shows that the model based on the modified momentum-profile theory is much closer to the real model. It can offer reliable characteristics of ducted propeller. The result of the numerical simulation and that of experiments have a good match, which can provide detailed design with reference.