连续变弯度翼型动态气动特性数值模拟

针对翼型后缘连续变弯度运动中后缘边界精确数值模拟的问题，提出了基于二维多项式的时空曲面拟合方法，实现了对后缘边界时空位置的精确模拟。在此基础上，基于OpenFOAM发展了翼型后缘连续变弯度与大幅度俯仰运动耦合的运动边界数值模拟，并计算了翼型耦合运动的气动力，讨论了后缘线性/非线性变形对翼型大迎角动态气动特性的影响规律。结果表明:后缘运动对翼型俯仰运动的升阻特性影响显著，特别在翼型大幅度俯仰时后缘非线性变形对升阻特性改善效果比线性变形大6%~10%。同时还研究了翼型俯仰与后缘变形运动相位差对气动特性的影响。特别地，当相位差为180°时，后缘运动使动态失速时的最大升力提高50.3%，平均升力提高34.6%；当2种运动相位差为0°时，后缘运动使动态失速时的最大阻力降低39.7%，平均阻力降低30.2%，最大升阻比提高22.3%，平均升阻比提高16.8%；同时，翼型在动态俯仰过程中出现负阻力现象，对产生负阻力的原因进行了分析。这些结果可用于指导连续变弯度后缘控制律的设计。 

Numerical simulation of dynamic aerodynamic characteristics of a camber morphing airfoil

In order to solve the problem of accurate numerical simulation of trailing edge morphing motion of a camber morphing airfoil, a spatiotemporal surface fitting method based on two-dimensional polynomial is proposed, which could accurately simulate the space-time position of the morphing trailing edge.On this basis, the numerical simulation method of the boundary motion caused by airfoil pitching motion and trailing edge morphing is developed in OpenFOAM, and the aerodynamic forces of the coupled motions of the airfoil are calculated. The results show that trailing edge motion has a significant influence on the lift and drag characteristics of the airfoil pitching motion, the effect of nonlinear deformation is 6%-10% greater than that of linear deformation in airfoil large-amplitude pitch motion. Meanwhile, the influence of phase difference between airfoil pitch motion and trailing edge motion on aerodynamic characteristics is discussed in this paper. In particular, when phase difference is 180 degree, trailing edge motion increases the maximum lift by 50.3% as well as the time-averaged lift by 34.6%. When phase difference is 0 degree, trailing edge motion reduces the maximum drag by 39.7% as well as the time-averaged drag by 30.2%. The maximum lift-drag ratio is increased by 22.3% and time-averaged lift-drag ratio by 16.8%. Meanwhile, during the airfoil pitching motion, negative drag coefficient is observed and the inducement is discussed. The above results provide important reference for the design of control law based on camber morphing airfoil.