The classical aerodynamic derivative model is widely used in flight dynamics, but its application is extremely limited in cases with complicated nonlinear flows, especially at high angles of attack. A modified nonlinear aerodynamic derivative model for predicting unsteady aerodynamic forces and moments at a high angle of attack is developed in this study. We first extend the higher-order terms to describe the nonlinear characteristics and then introduce three more influence parameters, the initial angle of attack, the reduced frequency, and the oscillation amplitude, to correct the constant aerodynamic derivative terms that have higher-order polynomials for these values. The improved nonlinear aerodynamic derivative model was validated by using the NACA 0015 airfoil and the F-18 model. The results show that the improved model has a higher prediction ability at high angles of attack and has the ability to predict the aerodynamic characteristics of other unknown states based on known unsteady aerodynamic data, such as the initial angle of attack, reduced frequency, and oscillation amplitude.

中文翻译：

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飞机大迎角改进的非线性气动导数模型

经典气动导数模型在飞行动力学中应用广泛，但在复杂非线性流动的情况下，尤其是大迎角情况下，其应用极为有限。本研究开发了一种改进的非线性空气动力导数模型，用于预测大迎角下的非定常空气动力和力矩。我们首先扩展高阶项来描述非线性特性，然后引入另外三个影响参数，初始攻角、降低的频率和振荡幅度，以校正具有高阶多项式的恒定气动导数项这些值。采用NACA 0015翼型和F-18模型对改进后的非线性气动导数模型进行了验证。