超声速弹丸诱导爆轰波的无网格数值模拟

为研究锥角对超声速弹丸诱导爆轰波形态的影响,发展了耦合有限速率化学反应模型的最小二乘显式无网格算法,其流体动力学采用含化学反应源项的多组分Euler方程建模,对流项和时间项分别采用多组分HLLC(Harten-Lax-van Leer-Contact)格式和四阶Runge-Kutta法计算。对尖劈诱导斜爆轰以及激波诱导燃烧流场进行了模拟,验证了算法的有效性。最后对等当量比甲烷/空气预混气体中,不同锥角弹丸诱导爆轰波流场进行了模拟,云图同实验阴影照片吻合较好,结果表明当锥角处于70°~100°时,易形成驻定斜爆轰波;锥角较小不利于可燃混合气体的点燃,仅能形成驻定斜激波;过大的锥角将导致爆轰波的脱体。     

燃油微喷嘴加工质量对雾化特性的影响及工艺优化

燃油微喷嘴的雾化性能影响航空发动机燃烧室的燃烧性能，微铣削加工后微喷嘴表面的加工残留和毛刺是导致雾化性 能不达标的重要原因。为了研究壁面加工质量对燃油喷嘴雾化性能的影响规律并制定相应的工艺解决方案，建立了微喷嘴的加 工残留模型和毛刺模型，采用计算流体动力学方法研究加工残留和毛刺对微喷嘴雾化性能的影响机理及规律。结果表明：壁面加 工残留和毛刺均有利于促进液体破碎，形成的雾滴粒径更小，壁面残留导致喷雾锥角过大且均匀度差，但毛刺主要导致雾化均匀 度差。为了降低燃油喷嘴内表面粗糙度，减少壁面毛刺，采用聚甲基丙烯酸甲脂（PMMA）毛刺抑制技术和微细喷砂技术进行工艺 优化，结果表明：PMMA毛刺抑制技术和微细喷砂技术均可应用于喷嘴加工，分别使壁面粗糙度降低23%和30%，表面粗糙度从 0.83 μm分别降低到0.64 μm和0.58 μm。2种技术均能够显著抑制切削加工毛刺和去除切削加工残留。     

Measuring air traffic complexity based on small samples

Air traffic complexity is an objective metric for evaluating the operational condition of the airspace.It has several applications,such as airspace design and traffic flow management.Therefore,identifying a reliable method to accurately measure traffic complexity is important.Considering that many factors correlate with traffic complexity in complicated nonlinear ways,researchers have proposed several complexity evaluation methods based on machine learning models which were trained with large samples.However,the high cost of sample collection usually results in limited training set.In this paper,an ensemble learning model is proposed for measuring air traffic complexity within a sector based on small samples.To exploit the classification information within each factor,multiple diverse factor subsets (FSSs) are generated under guidance from factor noise and independence analysis.Then,a base complexity evaluator is built corresponding to each FSS.The final complexity evaluation result is obtained by integrating all results from the base evaluators.Experimental studies using real-world air traffic operation data demonstrate the advantages of our model for small-sample-based traffic complexity evaluation over other stateof-the-art methods.     

状态预测神经网络控制应用于小型可回收火箭

随着商业航天的到来，可重复使用运载器的研究受到广泛关注，以SpaceX为代表的商业航天公司研发的部分可回收火箭表现出了前所未有的竞争力。为了研发可回收火箭技术，翎客航天利用民间工业力量研制了RLV-T3小型可回收火箭验证机，并在该验证机上通过数百次试验逐渐掌握了垂直起降（VTVL）技术。主要介绍了翎客航天在VTVL技术中的一项动力控制技术，提出了状态预测神经网络控制（SPNNC）算法。该算法具有鲁棒性强、适用范围广、控制参数易调整等优点。详细地描述了该算法的原理，并通过Simulink对SISO和MIMO 2种系统进行了仿真。同时详细地论述了将状态预测神经网络控制算法应用于RLV-T3小型可回收火箭的飞行及回收的试验，包括RLV-T3小型可回收火箭的基本特点、控制难点、存在的问题，飞行过程中各物理量的曲线和试验结论。经试验验证，状态预测神经网络控制算法具有良好的控制性能，基于该控制技术，即状态预测神经网络控制算法的RLV-T3小型可回收火箭验证机可以安全地实现垂直起飞、弹道飞行、空中悬停、软着陆回收全流程。     

基于改进的磁场检验和主方向算法的行人航向估计

针对以惯导为核心的行人定位算法存在航向角失真的问题，提出了一种融合惯性测量单元(IMU)和磁力计的行人导航算法，利用步幅航向的变化量将行人的运动分为直线行走和曲线行走两部分，当检测到行人直线行走时，提出一种实时建立主方向的自适应航向角漂移修正算法，对航行角误差进行补偿；当行人曲线行走时，辅助地磁场信息，使用磁场强度、地磁倾角、惯性导航系统(inertial navigation system，INS)与磁力计解算的航向角之差这三个特征值构建广义似然比检验量，对磁场进行判断获得稳定状态磁场信息，通过卡尔曼滤波对航向角误差进行补偿。将传感器置于足部进行实验，实验结果表明,两种算法可以实现优势互补，有效地抑制地磁信息的干扰，提高导航精度，算法结果相对于无航向角修正的零速修正算法、零角速度更新算法和单独使用磁力计进行融合的算法，定位误差分别降低了91.02%、82.93%和61.39%，室外和室内终点定位误差分别为4.545 4 m和0.543 6 m，占总路程的0.69%和0.17%。     

弹道导弹中段突防红外诱饵空域设计研究

对弹道导弹中段红外诱饵突防过程进行了研究,并根据建模与仿真方法对诱饵空域设计方法进行了研究,该方法基于弹头与诱饵的运动学模型、导引头识别模型、突防效果评价模型,通过搜索法和模拟退火算法分析不同空域构型下的诱饵目标群突防效果,最后对特定条件下诱饵空域构型突防效果进行了仿真计算,试验结果表明该方法具有科学性和工程应用价值.     

An aviation oxygen supply system based on a mechanical ventilation model

At high altitudes, an Aviation Oxygen Supply System(AOSS) protects pilots from low pressure and hypoxia by continuously providing oxygen corresponding to the pilots' dynamic respiratory properties.An AOSS mainly consists of oxygen supercharging machines which are used in a high-altitude flight cabin to supply pressurized oxygen to pilots.Therefore, it is of great significance to study the airflow dynamic characteristics of an AOSS for safe, continuous, and efficient oxygen supply.In this paper, an AOSS is firstly simplified and considered as a mechanical ventilation system.Then, its corresponding mathematical model is constructed.Next, to verify the mathematical model, a prototype AOSS with a lung simulator is proposed for an experimental study.Afterwards, to build a foundation for the optimization of the AOSS, the airflow dynamic characteristics of an aircraft are analyzed, and the effects of key parameters on the respiration system are researched.Through experimental and simulation studies, it can be concluded that the mathematical model is effective.Subsequently, for stability during the respiration process, we consider setting the equivalent throttling areas of the inspiration and expiration pipelines smaller within certain limits; additionally, an excessively high oxygen supply pressure will disturb smooth airflow, and in a low-pressure environment, the pressure can be 84 cm H_2O lower than the standard atmospheric pressure.This research can be referred to in the design of an oxygen supply system and the study on optimization of airflow dynamic characteristics.     

一种新型的充放电及分流一体化空间电源控制技术

为满足卫星轻量化需求,本文对一体化的空间电源调节技术进行了研究。采用一种新型的集蓄电池充放电与并联分流一体化功率拓扑结构和功率调节控制策略,可实现使用单一电路完成太阳阵分流、电池充电控制、电池放电调节三种功能。介绍了新型拓扑的工作模式、功率调节控制策略及其实现方法,通过Pspice软件进行了电路建模与原理仿真,结果证明此方法有效。     

基于ALT和MCMC方法的产品外场可靠性评估方法

针对目前基于加速试验产品可靠性分析方法忽略外场环境的差异性及未考虑外场数据等问题,从数据融合的角度,考虑试验与外场环境的差异性,综合加速寿命试验的试验数据和现场数据2种信息,建立更为准确的模型,并利用马尔科夫链蒙特卡洛(MCMC)进行贝叶斯分析,解决模型复杂难于计算的问题,通过Gibbs抽样获得模型后验参数估计,从而对产品在外场工作状况下的寿命及可靠性进行评估,最后通过实例对比分析,说明综合2种数据来源不仅扩大了信息量,同时评估的精度更高,结果更加可信。     

Aerodynamic configuration integration design of hypersonic cruise aircraft with inward-turning inlets

In this work,a novel airframe/propulsion integration design method of the wing-body configuration for hypersonic cruise aircraft is proposed,where the configuration is integrated with inward-turning inlets.With the help of this method,the major design concern of balancing the aerodynamic performance against the requirements for efficient propulsion can be well addressed.A novel geometric parametrically modelling method based on a combination of patched class and shape transition (CST) and COONs surface is proposed to represent the configuration,especially a complex configuration with an irregular inlet lip shape.The modelling method enlarges the design space of components on the premise of guaranteeing the configuration integrity via special constraints imposed on the interface across adjacent surfaces.A basic flow inside a cone shaped by a dual-inflection-point generatrix is optimized to generate the inward-turning inlet with improvements of both compression efficiency and flow uniformity.The performance improvement mechanism of this basic flow is the compression velocity variation induced by the variation of the generatrix slope along the flow path.At the design point,numerical simulation results show that the lift-to-drag ratio of the configuration is as high as 5.2 and the inlet works well with a high level of compression efficiency and flow uniformity.The design result also has a good performance on off-design conditions.The achievement of all the design targets turns out that the integration design method proposed in this paper is efficient and practical.