基于Hybrid State A* 与增强安全管道的直升机低空航迹规划

直升机低空突防已逐渐成为现代空战察打任务的核心,而低空航迹规划算法是实现该技术的关键。 尽管现有的航迹规划算法已经被应用于实际低空突防任务,但基于“前端- 后端”式的传统航迹规划算法依然 存在规划航迹机动执行性差与复杂动态场景下易碰撞的缺陷。针对上述问题,本文提出一种基于Hybrid State A* 与增强安全管道的改进算法。首先,基于Hybrid State A* 算法的联合轨迹优化,可以在状态空间中完成兼 顾直升机机动特性的初始航迹高效搜索,有效保证直升机航迹的可达性。其次,基于初始航迹膨胀的增强安全 管道,将后端航迹优化参数限制在安全的可行域内,进而有效提升复杂动态场景下规划航迹的安全性。在实验 环节,本研究结合ROS 机器人仿真环境与Rviz 数据可视化工具完成仿真验证,通过算法间的综合对比实验, 论证了本研究所提算法对规划的航迹机动性与安全性有明显的提升。     

虚拟现实技术在某民机培训中的应用

虚拟现实技术是20世纪兴起的一项综合性技术,随着科学技术的发展,该技术得到了快速的发展及广泛的应用。针对传统民机培训中存在的课程枯燥、培训效率低下以及成本高昂等问题,虚拟现实技术被逐步应用到民机培训中,并得到长足的发展。对某民机培训中心搭建的虚拟现实培训系统进行了介绍,包括大型沉浸式、头盔式及桌面式三种虚拟现实培训平台,详细介绍了以上三种虚拟现实培训系统的软、硬件组成,包括显示系统、交互设备及开发软件等;并对三种虚拟现实培训系统的优缺点进行了简要总结。针对培训内容在开发过程中存在的复杂、繁琐问题,介绍了基于Unity 3D开发引擎且适用于三种虚拟现实培训系统的无编程课件开发流程。最后对虚拟现实技术在民机培训中的发展方向进行了展望。     

基于MADS算法与嵌套网格技术的多段翼型优化设计方法研究

基于MADS算法、嵌套网格技术以及刚性动网格技术,以求解RANS方程为气动特性分析方法,对某大型客机带增升装置的多段翼型着陆构型下的缝道、重叠量和偏转角等参数进行优化设计,结果显示,该方法有较高的优化效率及计算精度。     

垂直度误差对复合材料单钉连接性能的影响

为揭示连接孔垂直度误差对航空复合材料连接性能的影响规律,对准各向同性碳纤维环氧树脂复合材料板进行了单钉单剪试验研究。以极限承载强度、弦刚度、2%偏移承载强度为指标研究连接孔的倾斜角度、倾斜方向以及螺栓扭矩对接头承载性能的影响规律。试验结果表明:当连接孔倾斜角度从0°增加到4°时,接头弦刚度增大10%~40%,极限承载强度下降9%~12%;连接孔倾斜方向对极限承载强度影响甚微,却可使接头弦刚度产生20%~30%的变化;增加螺栓扭矩可以有效提高极限承载强度,但对接头刚度无明显影响;连接孔倾斜角度越大,则螺栓扭矩的增大对2%偏移承载强度的强化效果越不明显。     

Improving the process forming limit considering forming defects in the transitional region in local loading forming of Ti-alloy rib-web components

The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local load ing process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element (FE) simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increas ing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology (RSM).The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the pro cess forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great impor tance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components.     

Aerodynamic multi-objective integrated optimization based on principal component analysis

Based on improved multi-objective particle swarm optimization (MOPSO) algorithm with principal component analysis (PCA) methodology,an efficient high-dimension multiobjective optimization method is proposed,which,as the purpose of this paper,aims to improve the convergence of Pareto front in multi-objective optimization design.The mathematical efficiency,the physical reasonableness and the reliability in dealing with redundant objectives of PCA are verified by typical DTLZ5 test function and multi-objective correlation analysis of supercritical airfoil,and the proposed method is integrated into aircraft multi-disciplinary design (AMDEsign) platform,which contains aerodynamics,stealth and structure weight analysis and optimization module.Then the proposed method is used for the multi-point integrated aerodynamic optimization of a wide-body passenger aircraft,in which the redundant objectives identified by PCA are transformed to optimization constraints,and several design methods are compared.The design results illustrate that the strategy used in this paper is sufficient and multi-point design requirements of the passenger aircraft are reached.The visualization level of non-dominant Pareto set is improved by effectively reducing the dimension without losing the primary feature of the problem.     

一种新颖的在线自校正死区补偿策略

为解决正弦脉宽调制(SPWM)电压源逆变器在低频和轻载时死区效应所导致的相电压、相电流畸变和转矩脉动等问题,提出了一种新颖的在线自校正死区补偿策略。该策略考虑了死区时间、功率器件管压降、开通时间、关断时间等对逆变器输出电流的影响,而且对直流母线电压和载波频率的波动进行了自校正在线计算补偿。最后,对输出电流进行了死区补偿前和补偿后的对比试验,结果表明该方法具有较好的补偿效果。     

敞口式离心喷嘴内部流动特性的试验及模拟

为了研究敞口式离心喷嘴内部流动特性,包括填充过程及结构参数和工作参数对流量系数及液膜厚度的影响,对7个不同切向孔直径及长径比的喷嘴展开了试验和数值模拟。采用高速背光对透明敞口式离心喷嘴进行光学测量,喷注压降从0.1~0.8MPa,结合数值模拟研究了旋流室内液膜的填充过程,捕获了空心涡形成及发展过程,得到了敞口式离心喷嘴液膜厚度和流量系数随结构参数及工作参数的变化规律。研究发现几何特性参数越高,液膜厚度、流量系数和质量流量越低;低压降时流量系数随喷注压降升高而略微增加,当喷注压降达到临界值0.4MPa后,流量系数和液膜厚度几乎不变,最大波动分别为1.1%和6%。综合考虑工作参数及结构参数,拟合流量系数及质量流量经验公式,最大偏差皆不超过10%。     

SJ-17卫星LHT-100霍尔电推进系统飞行试验工作性能评价

为了验证霍尔电推进系统的空间环境适应性、与航天器的相互兼容性、空间工作特性及空间飞行性能与地面数据的差异性,LHT-100霍尔电推进系统搭载SJ-17新技术验证卫星开展了在轨飞行试验,对霍尔电推进系统在轨飞行试验结果进行了详细评价。结果表明:在整个飞行试验期间LHT-100霍尔电推进系统各项工作性能参数符合设计指标要求,其中推力79.5m N,比冲1531s,系统功率低于1.527k W,单次长时间工作8h,在轨系统开关机次数大于24次,在轨累计点火时间超过3028min,在轨飞行试验数据与地面试验数据具有很好的一致性。     

某电动飞机螺旋桨气动特性数值模拟与风洞试验

以某型电动飞机螺旋桨为研究对象,基于RANS方程和SST湍流模型的MRF方法对螺旋桨进行高精度滑流准定常数值模拟和性能计算。为了验证计算和设计的合理性,对该型螺旋桨进行了缩比模型风洞试验。试验结果表明,数值模拟计算结果与风洞试验数据吻合较好,证明该方法可为螺旋桨设计提供指导。