Response and Control of an Aircraft in the Presence of Wind Shear

1.给出了考虑飞机上方空间风分布影响的风切变气动力和稳定性导数的表达式。数值算例表明，纵向运动的特征值受机翼与水平尾翼之间的位置关系的影响。研究了风切变过程中风的时间变化效应，建立了加速度导数公式。结果表明，加速度对抛物面模运动有影响，由加速度引起的气动扰动力是不可忽略的。在风洞产生的各种风切变条件下，对二维翼尾组合模型的气动力进行了测量。结果表明，风场气动效应的理论表达式是正确的。定性地验证了力的存在依赖于风的加速度。通过对上述模型进行强迫振动，验证了稳定性导数的实验预报方法，并指出风切变效应是可以检测到的。提出了一种实时估计风速变化的方法：利用机载导航仪器、惯性导航系统等数据对地面风速进行最优估计，并将估计的地面风速与实测空速之差作为风速。仿真结果表明了该方法的有效性。自动飞行控制系统的实用性。作为一种最优调节器，应用该系统对抑制飞机阵风响应进行了仿真，验证了该系统在防止风切变引起的航向偏差方面的有效性。

1. Expressions for aerodynamic forces and stability derivatves in wind shear have been given considering effects of spatial wind distribution over the aircraft. It has been found by a numerical example that the eigenvalues of longitudinal motion are influenced by the potitional relation between the wing and the horizontal tail.2. Effects of temporal wind variation in wind shear have beeen investigated and formulation of acceleration derivatives has been made. It has been shown that the acceleration influences the phugoid-mode motion and the aerodynamic disturbance forces due to the acceleration cannot be neglected.3. Measurement of aerodynamic forces on a two-dimensional wing-tail combination model has been performed in various wind shear conditions generated in a wind tunnel. The results show the validity of the theoretical expressions for the aerodynamic effects of wind distribution. The existence of forces depending on the wind acceleration has also been verified qualitatively.4. A method of experimental prediction of the stability derivatives has been tested by giving forced oscillation to the afore-mentioned model, and it has been confermed that the effects of wind shear can be detected.5. A method of real-time onboard estimation of wind variation has been developed as follows: Optimal estimation of the ground speed is made by using the data of onboard navigational instruments, the inertial navigation system and others, and the difference between the estimated ground speed and the measured airspeed is considered as the wind speed. The results of simulation has shown the availability of the method.6. Utility of an automatic flight control system. operating as an optimal regulator, in preventing deviation of the flight course due to wind shear has been examined by a simulation applying the system for the alleviation of gust response of the aircraft and extent of the effectiveness has been found.