Unsteady aerodynamics modeling for flight dynamics application |
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Authors: | Qing Wang Kai-Feng He Wei-Qi Qian Tian-Jiao Zhang Yan-Qing Cheng Kai-Yuan Wu |
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Institution: | 1. State Key Laboratory of Aerodynamics, 621000, Mianyang, China 2. Computational Aerodynamics Institute, China Aerodynamics Research and Development Center, 621000, Mianyang, China 3. Scientific Research Base of Flight Technology and Safety, Civil Aviation Flight University of China, 618307, Guanghan, China
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Abstract: | In view of engineering application, it is practicable to decompose the aerodynamics into three components: the static aerodynamics,
the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow.
The first and the second components can be presented in conventional forms, while the third is described using a one-order
differential equation and a radial-basis-function (RBF) network. For an aircraft configuration, the mathematical models of
6-component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude
oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady
aerodynamics and unsteady aerodynamics, respectively. The results show that: (1) unsteady aerodynamics has no effect upon
the existence of trim points, but affects their stability; (2) unsteady aerodynamics has great effects upon the existence,
stability, and amplitudes of periodic solutions; and (3) unsteady aerodynamics changes the stable regions of trim points obviously.
Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics
is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall
maneuverability are analyzed by numerical simulation. |
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Keywords: | Unsteady aerodynamics · High angle of attack · Mathematical model · Flight dynamics · Bifurcation analysis · Post-stall maneuver |
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