高超声速飞行器推进系统建模

Modeling of hypersonic vehicles propulsion system

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.

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 than0.5saveragely.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.