Control-Oriented Modeling and Simulation on Rigid-Aeroelasticity Coupling for Hypersonic Vehicle

Since the subsystems of aerodynamics,propulsion,structure and so on in hypersonic vehicles involve characteristics of nonlinearity,strong coupling and uncertainty,and typical hypersonic vehicles adopt slender-body and wave-rider layout with widely-used lightweight materials,the accuracy of the modeling with a conventional rigid-body assumption is challenged.Therefore,a nonlinear mathematical longitudinal model of a hypersonic vehicle is established with its geometry provided to estimate aerodynamic force and thrust using hypersonic aerodynamics and quasi-one-dimensional flow with heat added and capture vehicle aeroelasticity using a single free-free Bernoulli-Euler beam model.Then the static and dynamic properties of the rigid and rigid-aeroelasticity coupling model are compared via theoretical analysis and numerical simulation under the given flight condition.Finally,a LQR controller for rigid model is designed and the comparable results are obtained to explain the aerolasticity influence on the control effect.The simulation results show that the aeroelasticity mode of slender-body hypersonic vehicles affects short period mode significantly and it cannot be simply neglected.

高超声速热气动弹性中结构热边界影响研究

基于分层求解思路研究结构热边界对高超声速飞行器全动舵面和翼面结构热气动弹性特性的影响。首先,基于CFD求解N-S方程得到热环境,在此基础上进行结构的瞬态热传导分析,进而分析结构由于温度梯度产生的热应力和温度对材料属性的影响下的模态固有特性,然后将结构振型插值到气动网格上,最后,通过求解Euler方程得到流动参数,基于CFD的当地流活塞理论计算气动力,在状态空间中进行了气动弹性分析。通过对4组结构模型进行热气动弹性分析,研究了结构热边界对舵面和翼面热气动弹性的影响,结果表明:对全动舵面而言,结构热边界首先会影响舵轴处结构的热传导过程及温度分布,进而对结构固有频率、频率间距、颤振速度以及颤振频率的变化产生的影响达到了16%。对翼面而言,结构热边界对结构固有频率、频率间距、颤振速度以及颤振频率的变化产生的影响约为1%。因此,工程实际当中,进行热气动弹性分析时应采用合理的结构热边界。

气动弹性影响下高超声速飞行器动力学建模与分析

高超声速飞行器通常采用轻质材料和细长升力体设计,导致受控刚体运动频率与结构振动频率趋于接近,给飞行器制导控制系统设计带来了巨大挑战。基于假设模态下建立了考虑变截面效应的高超声速飞行器自由梁结构动力学模型,对比了横截面梁和变截面梁模态振型和频率;考虑变截面效应后,振型变化较大,同时二、三阶模态频率均变小。给出了耦合气动弹性和飞行动力学的高超声速飞行器运动方程。在典型工况下,对比分析了刚体、常截面梁和变截面梁高超声速飞行器的平衡和动态特征,结果说明:变截面梁在平衡状态下附加攻角更大,系统在平衡点处开环不稳定性更大,同时非最小相位行为基本不变。