可重复使用空间飞行器的飞行控制

分析了空间飞行器飞行控制系统要解决的问题,空间飞行器的发展过程,各类空间飞行器飞行控制系统设计目的和主要特点,可重复使用的发射飞行器飞控系统的主要设计要求,在设计要求的确定,飞行控制律设计和飞行控制系统设计中要解决的关键技术.      

基于SAGWO算法的UCAVs动态协同任务分配

通过分析无人作战飞机（UCAV）优势概率和任务联合威胁以及定义任务时间,建立了以目标价值毁伤、编队损耗代价和时间消耗为性能指标的多无人作战飞机（UCAVs）多约束动态任务分配数学模型,采用改进的灰狼优化（GWO）算法对数学模型进行求解;针对基本GWO算法求解早熟的缺点,给出了自适应调整策略和跳出局部最优策略,引入了二次曲线控制方法;对UCAVs动态协同任务分配特点,设计了目标任务序列编码方式,提出了基于自适应GWO（SAGWO）算法的UCAVs多目标动态任务分配方法。从静态与动态2种情况分别对该方法进行仿真验证;仿真结果表明,该方法是有效的,相比较于其他算法,其优化过程快速精准。      

基于模糊逻辑的预测再入制导方法

在研究再入飞行器预测制导基础上,针对实时性要求,提出了一种基于模糊逻辑系统的模糊预测制导方法.首先研究分析了再入飞行器落点纵程与飞行高度、弹道倾角三者之间的联系;设计了以再入飞行器落点偏差和飞行高度为输入,弹道倾角角速度为输出的模糊逻辑系统;并在此基础上根据专家经验制定模糊规则,设计模糊预测制导算法.该方法避免了一般预测制导在形成弹道倾角修正指令时所需要的大量迭代运算,有效减小了预测制导指令的解算时间,为再入飞行器在再入过程中全程使用预测制导提供了可能.仿真结果表明:该方法实时性好,落点精度高,抗干扰能力强,且具有一定的工程实用价值.      

高超声速飞行器预设性能反演控制方法设计

为解决吸气式高超声速飞行器的飞行控制问题,提出了一种新型预设性能神经反演控制器设计方法。通过构造预设性能函数,保证速度跟踪误差和高度跟踪误差能够按照预设的收敛速度、超调量及稳态误差收敛至期望的区域,同时满足系统预设的瞬态性能和稳态精度。在反演控制设计结构下,引入径向基函数（RBF）神经网络对模型未知函数及不确定项进行逼近,提高了控制系统的鲁棒性。引入的RBF神经网络中仅有一个参数需要在线更新,有效提高了控制准确性,避免了通常反演控制方法中经常出现的"微分膨胀问题",并降低了计算量。通过仿真实验验证了所设计控制系统的有效性和可行性。      

基于编队控制的自适应HELLO更新算法

在无人机(UAVs)编队自组织网络中,针对无人机之间位置信息更新周期不合理,从而导致编队控制不稳定和控制开销过大的问题,提出一种基于无人机编队控制的自适应HELLO更新算法。该算法应用编队控制稳定性理论推导出无人机组成期望编队的控制延时上限,结合该延时上限和编队运动状态自适应地设定HELLO更新周期。仿真结果表明,本文提出的算法与固定HELLO更新周期算法相比,既能保证在组编控制过程的稳定性,又能实时维护稳定阶段的链路,并且显著减少网络中不必要的控制开销。      

高超声速飞行器在中间大气层内的飞行速度研究

基于FLUENT软件, 采用Sp-A湍流模型并运用AUSM计算格式,通过对球头模型在高超声速来流下的外流场模拟,得到了该模型在30km,45km,53km,60km和75km高度处,满足氧化铝陶瓷最大使用温度的极限飞行马赫数。结果表明：在53km以下时,极限马赫数随高度增加而减小,之后再增大,变化趋势符合气温变化规律,静温对驻点处的最高温影响巨大。     

Prediction of shock-layer ultraviolet radiation for hypersonic vehicles in near space

A systemic and validated model was developed to predict ultraviolet spectra features from the shock layer of near-space hypersonic vehicles in the ‘‘solar blind" band region. Computational procedures were performed with 7-species thermal non-equilibrium fluid mechanics, finite rate chemistry, and radiation calculations. The thermal non-equilibrium flow field was calculated with a two-temperature model by the finite volume technique and verified against the bow-shock ultra-violet(BSUV) flight experiments. The absorption coefficient of the mixture gases was evaluated with a line-by-line method and validated through laboratory shock tube measurements. Using the line of sight(LOS) method, radiation was calculated from three BSUV flights at altitudes of 38,53.5 and 71 km. The investigation focused on the level and structure of ultraviolet spectra radiated from a NO band system in wavelengths of 200–400 nm. Results predicted by the current model show qualitative spatial agreement with the measured data. At a velocity of 3.5 km/s(about Mach11), the peak absolute intensity at an altitude of 38 km is two orders of magnitude higher than that at 53.5 km. Under the same flight conditions, the spectra structures have quite a similar distribution at different viewing angles. The present computational model performs well in the prediction of the ultraviolet spectra emitted from the shock layer and will contribute to the investigation and analysis of radiative features of hypersonic vehicles in near space.     

Drag derived altitude aided navigation method

The navigation problem of the lifting reentry vehicles has attracted much research interest in the past decade.This paper researches the navigation in the blackout zone during the reentry phase of the aircraft,when the communication signals are attenuated and even interrupted by the blackout zone.However,when calculating altitude,a pure classic inertial navigation algorithm appears imprecise and divergent.In order to obtain a more precise aircraft altitude,this paper applies an integrated navigation method based on inertial navigation algorithms,which uses drag derived altitude to aid the inertial navigation during the blackout zone.This method can overcome the shortcomings of the inertial navigation system and improve the navigation accuracy.To further improve the navigation accuracy,the applicable condition and the main error factors,such as the atmospheric coefficient error and drag coefficient error are analyzed in detail.Then the damping circuit design of the navigation control system and the damping coefficients determination is introduced.The feasibility of the method is verified by the typical reentry trajectory simulation,and the influence of the iterative times on the accuracy is analyzed.Simulation results show that iterative three times achieves the best effect.     

高超声速进气道附面层分离无源被动控制

为了控制超燃冲压发动机进气道唇口反射激波诱导的附面层分离,根据其流动特征,提出了附面层泄除-吹除互相驱动的自适应、无源、被动控制方案。并采用空间HLLE格式、LU-SGS隐式推进、多块结构网格的有限体积法数值模拟程序对该流动现象进行了数值模拟。数值结果表明,施加自适应无源被动控制后,分离区长度减小为无控制时的45%,控制区域的总压恢复系数和流场均匀性提高。从而证实了自适应、无源、被动控制抑制高超声速进气道附面层分离的可行性。     

A swept fin-induced flow field with different height mounting gaps

In order to apply the air fin successfully and ensure the maneuverability of hypersonic vehicle, a key problem to be studied urgently is the heat flux brought by the fin mounting gap. The appearance of mounting gap and fin shaft can induce many complex flow structures which need more attentions to be investigated. Under Ma 6, Nano-tracer-based Planar Laser Scattering (NPLS) and Temperature Sensitive Paints (TSP) were applied to visualize and measure transient flow structures and heat flux distribution of a swept fin-induced flow field with different height mounting gaps. Complementarily, Reynolds-averaged N-S equations were solved with k-ω SST turbulent model. The heat flux distribution results of numerical simulation and TSP observed the change of high heat flux region with different mounting gap, both in position and magnitude. The streamlines based on Computational Fluid Dynamics (CFD) and flow visualization results obtained by NPLS revealed the cause of high heat flux region. The high heat flux region in this flow field is mainly related to the reattachment of vortex and flow stagnation. The increase of gap height can lead to stronger gap overflow and shaft-induced horseshoe vortex, which are source of the high heat flux around the fin. The case with the highest mounting gap (4 mm) en-counters the most severe aerodynamic heating, both on the surface of fin and plate. Thus, under the premise of ensuring the flexibility of the fin, the gap should be set as small as possible.