无动力自动着陆轨道的鲁棒性分析

文中定义了能量梯度的概念,作为评价能量积累和消耗能力的指标。针对跨大气层飞行器对象特性的特点,重点讨论了气动参数的不确定性存在时的着陆点性能、整个下滑轨道容许的气动参数的不确定性范围和对初始动压的抑制能力,结果表明下滑轨道具有较好的鲁棒性。     

Aircraft robust multidisciplinary design optimization methodology based on fuzzy preference function

This paper presents a Fuzzy Preference Function-based Robust Multidisciplinary Design Optimization (FPF-RMDO) methodology. This method is an effective approach to multidisciplinary systems, which can be used to designer experiences during the design optimization process by fuzzy preference functions. In this study, two optimizations are done for Predator MQ-1 Unmanned Aerial Vehicle (UAV): (A) deterministic optimization and (B) robust optimization. In both problems, minimization of takeoff weight and drag is considered as objective functions, which have been optimized using Non-dominated Sorting Genetic Algorithm (NSGA). In the robust design optimization, cruise altitude and velocity are considered as uncertainties that are modeled by the Monte Carlo Simulation (MCS) method. Aerodynamics, stability and control, mass properties, performance, and center of gravity are used for multidisciplinary analysis. Robust design optimization results show 46% and 42% robustness improvement for takeoff weight and cruise drag relative to optimal design respectively.     

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS) under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP) allocator to generate torque com-manded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effective-ness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP) techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.     

A hybrid lattice Boltzmann flux solver for integrated hypersonic fluid-thermal-structural analysis

In this paper, a hybrid Lattice Boltzmann Flux Solver (LBFS) with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural problems. In the solver, the macroscopic Navier–Stokes equations and structural heat transfer equation are discretized by the finite volume method, and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann equation. To compute the numerical fluxes, two equilibrium distribution functions are introduced. One is the D1Q4 discrete velocity model for calculating the inviscid flux across the cell interface of Navier–Stokes equations, and the other is the D2Q4 model for evaluating the flux of structural energy equation. In this work, a new dual thermal resistance model is proposed to calculate the thermal properties at the fluid–solid interface. The accuracy and stability of the present hybrid solver are validated by simulating several numerical examples, including the fluid-thermal-structural problem of cylindrical leading edge. Numerical results show that the present solver can accurately predict the thermal properties of hypersonic fluid-thermal-structural problems and has the great potential for solving fluid-thermal-structural problems of long-endurance high-speed vehicles.     

嵌入式大气数据测量系统技术研究进展

针对高超声速飞行器大气数据测量问题，对嵌入式大气数据测量系统(FADS)技术研究背景、发展历程、国内外研究现状等进行了概括。重点围绕FADS关键技术、FADS解算算法及面向FADS/INS组合测量系统信息融合算法方面，对FADS技术进行了深入的剖析。最后，展望了FADS技术未来的发展方向及应用前景。     

A parameterized geometry design method for inward turning inlet compatible waverider

Intensive studies have been carried out on generations of waverider geometry and hypersonic inlet geometry. However, integration efforts of waverider and related air-intake system are restricted majorly around the X43A-like or conical flow field induced configuration, which adopts mainly the two-dimensional air-breathing technology and limits the judicious visions of developing new aerodynamic profiles for hypersonic designers. A novel design approach for integrating the inward turning inlet with the traditional parameterized waverider is proposed. The proposed method is an alternative means to produce a compatible configuration by linking the off-the-shelf results on both traditional waverider techniques and inward turning inlet techniques. A series of geometry generations and optimization solutions is proposed to enhance the lift-to-drag ratio. A quantitative but efficient aerodynamic performance evaluation approach （the hypersonic flow panel method） with lower computational cost is employed to play the role of objective function for opti- mization purpose. The produced geometry compatibility with a computational fluid dynamics （CFD） solver is also verified for detailed flow field investigation. Optimization results and other numerical validations are obtained for the feasibility demonstration of the proposed method.     

入口温度剖面对喷管流场结构的影响

应用质量平均的Navier-Stokes方程和B－L代数湍流模型，对超燃冲压发动机尾喷管的流场进行了数值模拟研究，在计算过程中，对方程中的对流项采用了空间为二阶精度的TVD格式，扩散项则采用了二阶中心差分离散，通过数值模拟，对比研究了温度非均匀性，三维效应对尾喷管的流场结构的影响。     

高超侧压式进气道高焓脉冲风洞实验

为验证一种双楔顶压、侧板中置的侧压式进气道基本性能,设计了一套进口面积为110mm×91mm的双流道试验模型,并在300mm马赫数6的高焓脉冲风洞中进行了吹风实验。实验测量了进气道和隔离段内的沿程静压分布和隔离段进出口截面的皮托压力分布,分析了进气道内的典型流场特征,获得了进气道的基本性能参数,并以马赫数的测量为例阐述了流场不均匀性对测量结果可能造成的影响。实验结果表明,马赫数6来流条件下,该侧压式进气道流量系数为0.83,隔离段出口平均马赫数为2.57,总压恢复系数为0.296,增压比为23.7,表明这种侧压式进气道的气动布局方式能够获得较好的总体性能。     

吸热型碳氢燃料用SAPO-34催化剂的合成与性能

采用三乙胺为有机模板剂，异丙醇铝为铝源，硅酸四乙酯为硅源，用水热法合成新型SAPO－34硅磷酸铝分子筛催化剂。通过X射线衍射、扫描电镜、红外光谱等方法对该新型催化剂的结构进行了分析，并研究了其热稳定性、表面组成及催化性能。实验结果表明，SAPO－34分子筛催化剂有高的不饱和烯烃选择性，说明是一类很有发展前景的吸热型碳氢燃料用的催化剂。     

二维高超声速压缩面斜激波系的优化配置

选择进气道外压缩段的气流转折角为设计变量,以进气道的压升比为约束条件,分别以总压恢复系数和阻力系数为优化目标,基于一维气体动力学,在飞行马赫数6,飞行高度25 km,进气道出口气流方向与自由来流夹角等于0,°2,°4°和6°的条件下,对二维混压式高超声速进气道进行了优化设计,得到了优化的斜激波配置。优化结果表明,在所讨论的各种情况下,以阻力系数最小为目标得到的外压缩段斜激波系与以总压恢复系数最大为目标得到的外压缩段斜激波系基本相同,都近似为等强度斜激波系。运用数值模拟手段验证了等强度斜激波系配置原则,本文提供的方法可以用于二维混压式高超声速进气道的初步设计。