吸气式内外流一体化飞行器动导数数值模拟

摘要

Dynamic derivatives are important parameters for designing aircraft trajectory and attitude control system,and for deciding the divergence behavior of vibration under disturbance. After calibration model validation,the dynamic behavior of an air—breathing hypersonic vehicle, namely WR—A (Wave Rider)is characterized.The unsteady flow field around the under aircraft forced simple harmonic vibration (SHV)condition is simulated using Navier Stokes equation. The direct damping derivatives,acceleration derivatives and rotary derivatives of this air—breathing hypersonic vehicle are obtained.The air inlet performance parameter derivatives are solved using Etkin predictive aerodynamic model.The air inlet performance parameters under large—amplitude vibration are successfully predicted using the dynamic derivative model.This offers a guideline for characterizing the dynamic unsteady internal flow field and predicting air inlet performance variation.The proportion of acceleration derivative,which represents the flow time lag effect,in the direct damping derivative can be as high as forty percent but is opposite to the damping deriv—ative direction in some cases,contributing to dynamic instability adversely.It is reasonable to using this dynamic derivative model to express the aerodynamic behavior of air—breathing hyper—sonic vehicle at large angles of attack according to this WR—A large—amplitude vibration simula—tion.%动导数是飞行器轨道及姿态控制系统设计时的重要参数，对飞行器开环系统受到扰动时振荡的敛散特性起重要作用。在标模验证的基础上开展吸气式内外流一体化飞行器 WR—A 动态特性分析，采用 N—S 方程模拟强迫简谐振动的非定常流场，获得了飞行器的直接阻尼导数、加速度导数和旋转导数，并对 WR—A 外形大振幅振动时的进气道性能参数进行了分析。研究表明，在某些情况下反映流动时滞效应的加速度导数占直接阻尼导数的比例最高可以达到40％以上，而在某些情况与直接阻尼导数符号相反。此外，在动导数研究基础上，采用参数化的动导数概念初步开展了非定常气动参数建模研究。针对 WR—A 大振幅强迫振动的研究显示，采用所建立的模型预测的气动参数与完全非定常计算吻合较好。