双旋翼微型飞行器的非定常气动特性

发展了一种基于计算流体力学(CFD)的非定常气动特性预测方法,计算方法包括了动量源模型、预处理方法、非结构嵌套网格和Spalart-Allmaras(S-A)湍流模型等技术.通过计算悬停Caradonna-Tung算例和俯仰振荡NACA0012算例,验证了计算方法模拟双旋翼微型飞行器动态流场的有效性.数值模拟了双旋翼微型飞行器动态流场,给出了非定常气动系数的迟滞曲线,分析了缩减频率、前飞速度和螺旋桨转速对非定常气动特性的影响.计算结果表明:力矩系数迟滞效应随缩减频率、前飞速度和螺旋桨转速增大而增大,升力系数迟滞效应随缩减频率和前飞速度增大而增大,但基本不随螺旋桨转速变化而变化. 

Unsteady aerodynamic characteristics of dual rotor micro air vehicle

A method based on computational fluid dynamics (CFD) was developed to predict the unsteady aerodynamic characteristics. The computational method includes numerous techniques such as momentum source model, preconditioning method, unstructured overset grids and Spalart-Allmaras (S-A) turbulence model. The effectiveness of the computational method in simulating dynamic flow field of dual rotor micro air vehicle was validated by calculating hovering Caradonna-Tung rotor and pitching NACA0012 airfoil. The dynamic flow field of dual rotor micro air vehicle was numerically simulated; the hysteresis curve of unsteady aerodynamic coefficient was calculated and the effects of reduced frequency, forward speed and propeller speed on unsteady aerodynamic characteristics were analyzed. The computational results show that the hysteresis effect of moment coefficient increases as induced frequency, forward speed and propeller speed increase, and the hysteresis effect of lift coefficient increases as induced frequency and forward speed increase, however, the hysteresis effect of lift coefficient changes slightly as the propeller speed changes.