高超声速飞行器推进系统建模

为在高超声速飞行器设计初期快速地获得推力和推力矩,以满足控制相关分析和建模需要.提出一种推进系统建模方法,基于激波/膨胀波相交理论来建模与机身耦合的进气道模型;用有摩擦变截面加热管来描述双模态燃烧室;将内喷管建模成一维变截面摩擦管,采用动量定理估算推力,并通过曲线拟合得到推力的解析表达式.与CFD计算结果相比,该模型计算得到双模态冲压发动机入口气流马赫数和温度误差小于5%,压强误差小于10%;计算得到的推力随马赫数、燃油当量比和迎角的增大而增加,随高度增加而减小,单个状态平均计算时间小于0.5s.计算结果表明:该建模方法满足面向控制建模的效率和精度需求,有助于此类飞行器设计初期的动力学和控制相关的分析和设计. 

Modeling of hypersonic vehicles propulsion system

In order to quickly obtain the thrust and moment of thrust at the early design stage, and satisfy relevant modeling and analysis control, a model for the propulsion system of hypersonic vehicle was proposed. An inlet model was developed based on the wave interaction method. Moreover, the dual-mode combustor was modeled by an increasing area duct with heat addition and friction, whereas the internal nozzle was modeled by a variable area duct with friction. Accordingly, the thrust was estimated according to the momentum theory, and then analytical expression was obtained by a curve-fitting method. Compared with the result of CFD, the error of Mach number and temperature at the dual mode ramjet engine inlet was less than 5%, and the pressure error was less than 10%; the computed thrust increased as Mach number, stoichiometrically normalized fuel-to-air ratio and angle of attack increased, and decreased as height increased; the time cost of one state point was less than 0.5s averagely. Computation result demonstrates that the proposed modeling approach meets the high efficiency and accuracy required in the control-oriented modeling process, contributing to the analysis and design related to dynamics and control of the hypersonic vehicles.