智能磁航向传感器的研制及误差补偿算法分析

介绍了微型智能磁传感器的设计,分析了影响磁航向精度的误差来源.在此基础上提出了基于BP神经元网络、最小二乘及最佳椭圆拟合等3种不同的磁航向误差补偿算法,详细分析了每种算法的工作原理,并立足于算法的具体实现,通过现场试验,从精度、速度、效率等3个方面对算法的有效性加以分析验证,并得出结论.      

具有复杂边界的火箭冲压发动机流场数值计算

针对实际复杂的补燃结构和计算边界,以块隐式法计算流场,用代数法生成计算网格,通过改变离散方程来处理三维定常Ｎ－Ｓ方程边界条件。算例表明,该方法正确可靠,迭代过程能够快速收敛。     

不同边界层厚度下高马赫数进气道自起动过程研究

为了探寻入口边界层厚度变化对高马赫数进气道自起动性能的影响,对简化的二元高马赫数进气道的加速自起动过程进行数值仿真研究,分析了边界层厚度对自起动过程中流场波系结构变化和自起动性能的影响机制,获得了不同边界层厚度下的进气道自起动性能及主分离包高度的变化规律。结果表明:随着边界层相对厚度从0.05增加至0.3,进气道的自起动马赫数一开始保持不变,然后快速增大;相同主流条件下,不起动流场跨越主分离包无量纲压升和主分离包高度随边界层相对厚度的增大均变小;边界层动量损失厚度和跨越主分离包无量纲压升对进气道起动性能影响重大。     

碳氢燃料热声不稳定流动特性和边界实验分析

为保障空-油换热器安全稳定运行,对竖直上升圆管内超临界压力航空燃料的热声不稳定流动进行了实验研究。阐述了管壁温度的振荡特征和热声不稳定流动的诱发原因。考察了运行参数对流动稳定工况和流动不稳定工况界限的影响。取相邻流动稳定工况和流动不稳定工况的热流密度平均值作为边界,分析了该边界随进口拟过冷度的变化情况。通过临界拟相变数和拟过冷度数的比值表征,建立了热声不稳定流动边界与进口雷诺数和相对压力关联的预测准则。结果表明:拟沸腾效应导致了热声不稳定流动现象。进口温度和运行压力越低,热声不稳定流动越容易出现。提出的边界预测准则具有较高的精度,与实验结果的相对偏差在±15%以内。     

Experimental investigation of boundary layer transition over a delta wing at Mach number 6

An experimental study on the boundary layer transition over a delta wing was carried out at Mach number 6 in a quiet wind tunnel. The Nano-tracer-based Planar Laser Scattering (NPLS) and Temperature-Sensitive Paints (TSP) techniques were used to measure the fine flow field structure and the wall Stanton number of the delta wing. The influence of factors such as the angle of attack and the Reynolds number was studied. The following results were obtained. The boundary layer transition between the leading edge and the centerline was dominated by the crossflow instability. At the location of the initial appearance of the traveling crossflow waves, the Stanton number began to rise. The Stanton number reached a maximum when the crossflow waves were broken up to turbulence. Increasing the angle of attack increased the spanwise pressure gradient at the windward side of the delta wing, thereby increasing the crossflow instability and advancing the boundary layer transition front. However, increasing the angle of attack caused the transition front to move backward at the leeward side. In addition, the sensitivity of the boundary layer transition to the Reynolds number varied with the angle of attack and the region.     

Inverse design of mission success space for combat aircraft contribution evaluation

This paper presents a novel design method of the Mission Success Space (MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the success by conventional mission effectiveness with regards to the aircraft capabilities. This space is created by the Mission Success Function (MSF) and the original Effectiveness Index Space (EIS) where empirical equations are usually assumed to be MSFs. Based on this MSS concept, this paper firstly defines the MSS-based evaluation, then further summarizes the evaluation process of the Contribution to System-of-Systems (CSS). More importantly, based on the thought of Inverse Design (ID), a new design method of MSF is presented comprehensively analyzing aircraft’s CSS in a combat mission without using any empirical MSF. The definition of MSS based ID is given and the design procedure is sequentially introduced. Two different confrontation cases are depicted with many details as the simulation validation: Air-to-ground and Penetration. There are two design variables considered for designing MSS in the latter case while only one for the former. However, in both cases, the best design is given by evaluating the Gaussian fitting performance of CSS.     

非设计状态下尾迹输运对高负荷低压涡轮附面层的影响

为了研究非设计状态下的上游尾迹在叶栅通道内的形态演化与发展,分析尾迹与叶片吸力面附面层的相互作用,基于高负荷低压涡轮(LPT)叶型Packb对非设计状态下尾迹输运进行了研究。研究主要通过数值模拟的方法进行,使用CFX软件,利用LES模型耦合Smagorinsky亚格子模型。讨论了非定常来流0°和+10°攻角工况下,尾迹与吸力面附面层相互作用的差异。分析发现,+10°攻角工况时,尾迹对附面层转捩的促进作用较0°攻角工况时更为显著;+10°攻角工况时,尾迹与附面层的相互作用时间更长,尾迹诱导转捩的起始位置更靠上游。     

电磁式跟踪器磁场畸变的姿态校正技术

电磁式跟踪器可以测量物体的位置和姿态,但其测量精度也容易受金属环境干扰。本文根据电磁跟踪器的工作原理,给出了电磁式跟踪器姿态校正的模型,讨论了两种不同的姿态校正实现方法:插值法和拟合法,比较了两种方法的优缺点。最后,对某一金属环境进行了畸变姿态校正的试验,给出了3个不同的姿态实际值和在此金属环境下的畸变和校正结果。试验结果表明本文提出的姿态校正算法能很好地补偿金属环境引起的电磁式跟踪器姿态的畸变。     

CAARC高层建筑标模动态测力研究

CAARC高层建筑标模的动态测力试验在南京航空航天大学NH－2低速风洞中进行，在均匀流场中以及模拟大气边界层中分别测量了模型的动态气动力和力矩的平均值，均方根值，峰值，试验目的是为检测NH－2风洞的大气层边界模拟技术，动态天平，测试仪器以及动态数据采集和处理系统，试验结果表明，CAARC标模的所有动态气动特性在NH－2中的测量值与国外部报导的结果符合得较好，因此，NH－2风洞的大气边界层模拟技术，动态天平，测试仪器以及动态数据采集与处理系统可以承担高层建筑方面动态测力试验任务。     

基于需用功率预测的直升机/发动机综合控制方法

为了提高涡轴发动机在直升机飞行状态突变时的响应速度,提出一种基于需用功率预测的直升机/发动机综合控制方 法。通过逐步回归分析法对直升机需用功率影响最大的5个变量进行选取,并以这5个变量为输入量,根据多元拟合方法建立直 升机需用功率预测模型,基于所建立的预测模型,采用预测需用功率信号在发动机控制回路的燃气涡轮转速指令位置进行前馈线 性补偿,设计了直升机/发动机综合控制方法。经过UH-60A综合仿真平台验证,结果表明：所提出的综合控制方法相比于传统串 级PID控制方法,可以有效减少动力涡轮转速超调量或下垂量60%以上;相比加入总距前馈的控制方法,可以减小动力涡轮转速 超调量或下垂量20%以上;可以有效加快发动机响应速度,缩短发动机响应时间1 s以上,极大提高了发动机的稳定性及鲁棒性。