基于任务段的航空发动机载荷谱聚类方法

针对航空发动机飞行任务剖面分类问题,对发动机31个飞行任务剖面进行了聚类分析。选取飞行高度和飞行马赫数作为划分飞行任务剖面的参数, 依据其对应的飞行任务段均值生成聚类散点图,将剖面类型划分为5大类。结果表明:低空低速剖面在无量纲飞行高度为0~0.2、飞行马赫数为0.4~0.6区间,均值最低;高空高速剖面在无量纲飞行高度为1.2~2.2、飞行马赫数为1.0~1.8区间,均值最高;飞行任务剖面在无量纲飞行高度为0.2~1.2、飞行马赫数为0.6~1.0区间内最为集中;针对散点密集区域,可依据剖面特征进一步划分剖面类型;不同剖面间,飞行高度与飞行马赫数差异性强,利于剖面划分,而法向过载与转速差异性小,不利于剖面的划分。所提出的方法可以快速有效的对航空发动机飞行任务剖面进行聚类分析。      

含面芯脱粘边缘闭合蜂窝壁板压缩稳定性研究

基于有限元软件ABAQUS,分别建立了无损伤和含板芯脱粘缺陷的边缘闭合蜂窝壁板的三维有限元模型。利用3种建模方法对比研究了边缘闭合蜂窝壁板在压缩载荷作用下的屈曲载荷规律和失稳模式。采用夹芯板理论将蜂窝芯等效为正交各向异性结构,板芯之间的胶层使用cohesive单元进行模拟。研究结果表明:随着脱粘尺寸的增加,蜂窝壁板的屈曲载荷呈现下降趋势;当30 mm≤D≤80 mm时结构由混合屈曲过渡到局部屈曲;两种等效模型发生局部屈曲后,无论是结构的屈曲载荷规律和屈曲载荷值还是失稳模式,均近似接近原始模型结果。     

频率稳定度与守时钟组配置关系研究CSCD

通过对中小型守时实验室对时间尺度稳定度的需求分析,以目前主流守时钟5071A为例,利用国际权度局公布的原子钟数据,研究不同钟组配置与时间尺度稳定度的关系,为中小时间实验室守时钟组的优化配置提供参考依据;权重确定是原子时算法的关键之一,通过对不同数量、不同取权规则的原子时计算结果进行统计分析与比较,提出中小时间实验室原子时尺度算法中的取权原则。     

基于Lagrange方法的单旋翼飞行器动力学建模

为了进行微小型单旋翼飞行器的动力学建模,通过建立多个坐标系来反映各部分间的相对运动.首先,利用坐标变换得到位置、速度及加速度等向量,并代入拉格朗日方程得到运动学模型;然后,对模型进行数值求解,得到飞行器的姿态响应.仿真结果表明,飞行器定点盘旋时合外力为零,能量保持不变;爬升或前飞时有非保守力做正功,能量增大.     

可重配置的试飞模拟器软件构架研制

试飞模拟器介于工程模拟器和训练模拟器之间,兼顾着工程和训练两方面的任务.在试飞模拟器研制、虚拟试飞应用的基础上,提出了一套完整的可重配置的试飞模拟器软件构架方案,主要包括研究内容、开发环境、开发方法以及系统体系结构.依据此方案研制了一套飞行软件包,并通过虚拟试飞进行了验证.结果表明:可重配置的试飞模拟器飞行软件包克服了...     

Experimental and numerical study of tip injection in a subsonic axial flow compressor

Parametric study of tip injection was implemented experimentally on a subsonic axial flow compressor to understand the underlying flow mechanisms of stability improvement of the compressor with discrete tip injection.Injector throat height varied from 2 to 6 times the height of rotor tip clearance,and circumferential coverage percentage ranged from 8.3％ to 25％ of the annulus.Static pressure fluctuations over the rotor tip were measured with fast-response pressure transducers.Whole-passage time-accurate simulations were also carried out to help us understand the flow details.The combinations of tip injection with traditional casing treatments were experi mentally studied to generate an engineering-acceptable method of compressor stall control.The results indicate that the maximum stability improvement is achieved when injectors are choked despite their different sizes.The effect of circumferential coverage percentage on compressor stabil ity depends on the value of injector throat height for un-choked injectors,and vice versa.Tip blockage in the blade passage is greatly reduced by the choked injectors,which is the primary reason for stability enhancement.The accomplishment of blockage diminishment is maintained in the circumferential direction with the unsteady effect of tip injection,which manifests as a hysteresis between the recovery of tip blockage and the recovery of tip leakage vortex.The unsteady effect is primarily responsible for the effectiveness of tip injection with a partial circumferential coverage.Tip injection cannot enhance the stability of the rotor with axial slots significantly,but it can improve the stabil ity of the rotor with circumferential grooves further.The combined structure of tip injection with circumferential grooves is an alternative for engineering application.     

在动态逆飞控系统中处理非定常气动力的方法

主要考虑大迎角非定常气动力对飞控系统的影响，并给出在动态逆飞行控制系统中的抑制这种影响的方法。非定常气动力表现在气动参数上是出现滞环现象，本文根据已成的成果，主要讨论与飞机纵向控制有关的问题。     

Nostoc sphaeroides Kützing,an excellent candidate producer for CELSS

Some phytoplankton can be regarded as possible candidates in the establishment of Controlled Ecological Life Support System (CELSS) for some intrinsic characteristics, the first characteristic is that they should grow rapidly, secondly, they should be able to endure some stress factors and develop some corresponding adaptive strategies; also it is very important that they could provide food rich in nutritious protein and vitamins for the crew; the last but not the least is they can also fulfill the other main functions of CELSS, including supplying oxygen, removing carbon dioxide and recycling the metabolic waste. According to these characteristics, Nostoc sphaeroides, a potential healthy food in China, was selected as the potential producer in CELSS. It was found that the oxygen average evolution rate of this algae is about 150 μmol O₂ mg⁻¹ h⁻¹, and the size of them are ranged from 2 to 20 mm. Also it can be cultured with high population density, which indicated that the potential productivity of Nostoc sphaeroides is higher than other algae in limited volume. We measured the nutrient contents of the cyanobacterium and concluded it was a good food for the crew. Based on above advantages, Nostoc sphaeroides was assumed to a suitable phytoplankton for the establishment of Controlled Ecological Life Support System. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food in future space missions.     

JJG 860-2015《压力传感器(静态)检定规程》浅析

介绍了JJG 860-2015《压力传感器(静态)检定规程》的主要变化,就检定设备的选择、特殊压力传感器的检定方法等对规程进行浅析,结合测试实例论述了新增传感器零点漂移和周期稳定性两个性能指标的必要性,并对规程的进一步完善提出了建议。     

通用飞机多约束水平航路规划方法研究

随着我国低空空域的开放,通用飞机低空航路规划问题越来越复杂,亟待解决。在传统航路规划方法的基础上,研究满足区域导航要求下低空空域的约束条件,并针对每一类约束条件,建立航路优化模型,给出航路优化算法的实现步骤。仿真实验验证表明,多约束水平航路规划方法能够满足通用飞机机载设备的功能和性能要求。