Elastic aircraft flight dynamics modeling method based on nonlinear aerodynamic force order reduction

Abstract

The invention provides an elastic aircraft flight dynamics modeling method based on nonlinear aerodynamic force order reduction, which is suitable for engineering and is used for realizing elastic aircraft flight dynamics simulation, especially gust response high-precision and high-efficiency simulation under the condition that a low-speed aircraft encounters large-amplitude gust. The method comprises the following steps: firstly, establishing a rigid-elastic coupling kinetic equation of the elastic aircraft, then solving generalized aerodynamic force in a given motion or incoming flow state based on CFD, and obtaining training input and output signals of a reduced-order model; an ARMA model and an RBF neural network model are adopted to establish a linear aerodynamic order reduction model and a nonlinear correction model respectively, and the linear aerodynamic order reduction model and the nonlinear correction model are combined to obtain a nonlinear aerodynamic order reduction model; and then coupling the nonlinear aerodynamic reduced-order model and the rigid-elastic coupling kinetic equation to carry out flight kinetic simulation on the elastic aircraft. Compared with a traditional simulation method based on surface element method aerodynamic force, the method is high in precision and efficiency compared with a CFD / CSD coupling analysis method, and has high engineering value.

Description

technical field [0001] The invention relates to an elastic aircraft flight dynamics modeling method based on nonlinear aerodynamic reduction. Background technique [0002] During the flight, the aircraft may be disturbed by gusts of different degrees. These disturbances change the effective angle of attack of the aerodynamic lift surface, resulting in sudden changes in aerodynamic forces, thereby making the body respond dynamically. On the one hand, it affects the ride quality and maneuverability of the aircraft, and on the other hand, it may even cause damage to the aircraft structure and cause flight safety accidents. However, the low-speed high-aspect ratio aircraft has more flexibility and lower wing load, and is more sensitive to additional aerodynamic disturbances caused by gusts. Therefore, it is necessary to simulate and analyze the flight dynamics and gust response characteristics of low-speed high-aspect ratio aircraft. [0003] In order to analyze the above probl...

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Problems solved by technology

[0006] The aerodynamic method used in the first type of method is a surface element analysis method suitable for linearity and small deformation, which cannot meet the accuracy requirements of nonlinear aeroelastic calculation under the condition of large aspect ratio aircraft, large angle of attack and large magnitude gusts.

[0007] The calculation principle of the second type of full-order analysis method is complicated, and it takes a lot of time from grid modeling to actual calculation, and the calculation efficiency is low, so it is not suitable for engineering applications

[0012] The first two types of models are often applied to linear aerodynamic reduction modeling, and the fitting ability for nonlinear situations is weak

The third type can model nonlinear unsteady aerodynamic forces under large motion ranges. However, due to the limitation of the amount of nonlinear training data, the generalization ability of this type of model is often not satisfactory. To solve this problem, it is necessary to increase Non-linear samples or changes in the neural network structure, the modeling cycle is long, not suitable for engineering problems that require multiple changes in working conditions parameters for rapid repeated calculations

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