高速飞机总静压探头的气动设计、仿真和测试

阐述了高速飞机总静压探头的气动设计、CFD仿真、风洞测试、飞行校测。通过旋成体理论实现总静压探头补偿型面在设计阶段的快速调整,通过商用CFD软件得出静压误差的仿真。设计的总静压探头气动性能需要通过风洞测试的验证,并最终通过飞行校测验证其是否满足使用要求。     

基于STM32F103C8T6的气动隔膜泵测试系统设计

由于气动隔膜泵在泵的行业中快速发展,传统的泵的测试系统,已经不能满足当前气动隔膜泵性能检测的需要。为解决这个问题,本文介绍了一种基于STM32F103 C8T6气动隔膜泵性能测试系统,采集气动隔膜泵测试系统的液体压力和流量参数,以及高压气体的压力和流量参数。分析了系统的需求,给出了系统的框架图,以及硬件设计框图;详细阐述了系统硬件和软件设计;实际应用证明,该测试系统具有成本低、功耗小、响应速度快等优点,并且实现MCU与上位组态的通讯,通过上位数据分析来判断气动隔膜泵性能的好坏。     

气动ABS压力调节器动态性能测试系统研究

阐述气动ABS压力调节器的工作原理及其在汽车气制动过程中的作用,从而引出气动ABS压力调节器的参数测试要求。针对ABS压力调节器的基本参数要求,提出气动ABS压力调节器动态性能测试方法,研究测试系统的具体实现方案,设计工控机、电磁阀驱动电路、传感器、压力产生装置、数据采集系统、制动系统和排气系统等主要单元,在实验室实现整个系统的组装并搭建控制和测试平台。实验数据表明:该系统具有较高的可靠性,在气压范围为0～12 MPa的条件下,气压测量准确度,测试精度高,稳定性好。     

关于局域网、城域网光纤测试

随着局域网络的发展，光纤在局域网的地位逐步提高，同时对于光纤测试的要求也在提高。本文从基础维护测试和认证测试两个方面解释了局域网光纤测试的主要概念和参数特点，其中包括通断测试、长度衰减测试，OTDR精度测试、以及常规维护测试等。同时，文章也简单介绍了各种光纤测试在光纤网络布线、施工、验收、维护、抢修中的应用。     

离合总泵综合性能测试系统研制

针对离合总泵性能测试项目单一,难以复测动态响应特性,引入高精度数据采集、伺服精密控制、气动比例抓取等技术,研制一套双工位综合性能测试系统。工位一用于密封测试,工位二用于动态行程及真空性测试,设计基于伺服线性滑台和抓取气缸的拾取机构,实现产品工位间的移动。基于功能模块化设计理念,系统以工控计算机为载体,数据采集与处理模块实现传感器信号的输入与调理,设计精密伺服加载机构复现实车环境下离合作业状态,基于LabVIEW开发测试软件。完成系统的标定与试验,引入测量系统分析开展重复性分析。结果表明:功能项测量能力指数Cg均≥1.67,量具RR贡献率30%,测试时间小于2 min/件,满足系统在线测试需求。     

电弧加热流场测温信号干扰分析

在电弧加热器流场的试验测试中,采用热电偶对模型温度等参数进行测试时,通常会受到电弧电势的严重干扰.本文对电弧电压和噪声信号的频谱进行分析,确定了电弧电压的渡动噪声是热电偶电势信号产生干扰的主要干扰源.采用测试模型与电弧加热器喷管电气隔离并分别接地等措施,解决了信号干扰问题,这对热电偶在电弧加热类气动防热试验流场测试中的...     

三主桁断面车-桥气动特性的风洞试验研究EI北大核心CSCD

为研究三主桁断面车-桥组合系统的气动特性。以某大跨度斜拉桥为工程背景,采用节段模型风洞试验,通过开发的车-桥气动力同步测试装置对车-桥组合状态下各自的气动力进行测试,研究了线路位置、双车交会间距、风攻角等因素对车-桥系统气动特性的影响,分析紊流来流对车-桥气动特性的影响,并讨论列车气动导纳的特征。结果表明:由于绕流剪切层的影响,靠近迎风侧车辆阻力系数大于其他线路,线路2上列车的升力系数最大;双车交会时,背风侧车辆的阻力系数和升力系数随交会间距的增大而增大;受桁架自身绕流的影响,紊流来流对列车气动力功率谱影响较小;阻力和升力的气动导纳随折减频率呈现先增后减的趋势。     

发动机稳定性试验研究VXI总线测试系统

发动机稳定性试验研究VXI总线测试系统是针对涡扇／涡喷发动机进行流场畸变试验以及气动稳定性试验研究装置而开发的测试系统，达到了国内先进水平，本文介绍了该系统的功能，技术指标，系统组成，工作原理和软件设计等。     

基于PXI总线的舵机性能测试平台

舵机是空空导弹控制系统的执行机构,舵机测试在导弹性能考核中有重要意义。为了满足对各种类型舵机性能测试的需求,搭建了一个通用化的基于PXI总线的舵机性能测试平台,系统能够实现电动与气动舵机的空载与加载性能测试。软件开发选用Lab Windows/CVI语言,采用多线程技术和模块化设计方法,具有很强的扩展性。应用结果表明:该系统操作简便、覆盖性广、通用性强、精度高,为舵机的性能研究、评估和改进提供了一个良好的工具。     

基于UKF、EKF飞行器气动参数辨识方法比较研究

在航空航天工业中,气动参数辨识广泛应用于飞机气动性能测试,随着飞机性能、操纵要求的提高,以及在线辨识实时性的需要,对气动参数辨识的精度、速度有了越来越高的要求。该文对扩展卡尔曼滤波模型(EKF)、无损卡尔曼滤波模型(UKF)、飞行器气动参数辨识模型进行理论分析。而后依据固定翼飞机飞行数据,结合二维飞行器运动模型,分别应用EKF算法、UFK算法对气动参数进行辨识,对两者的辨识过程和结果进行比较,为飞行器气动参数辨识中滤波算法的选择提供借鉴。     

Effect of a spherical explosion upon the flight path and spatial orientation of a projectile

A possible defense of an armored vehicle against a high-kinetic-energy projectile is based on generating a strong explosion in a close proximity of the projectile and at some distance from the vehicle. In this exposition we suggest a simplified analytical model that bounds the effect of an explosion upon the flight path and spatial orientation of the projectile.     

A simple defense conservative model for mass requirements of hypervelocity projectile impact shields for reentry vehicles

Simple analytical modeling of the physics of interaction of hypervelocity (50–100 km/s) projectiles with a bumper shield countermeasure is given. The interaction of projectile and bumper is discussed briefly. Expansion of bumper/projectile debris in the region between bumper and underlying vehicle and interaction of bumper/projectile debris cloud with vehicle are examined. Expansion of debris is treated as an expansion superimposed upon a translation with partition derived from a simple inelastic collision model. The effect of nonunity aspect ratio of compressed debris is included. Debris colliding elastically with the vehicle will impart momentum equal to twice the incident normal component. A steady-state diffusion model is used to estimate the effect of stagnation radiative loss on collision elasticity. Impulse may be reduced up to a factor of 2 by stagnation radiative losses for small projectiles and large bumper/vehicle stand-off. Stagnation radiation loss is small for larger projectiles and smaller stand-off. Impulse can be enhanced by vehicle ablation from radiative coupling, shock heating (inadequate stand-off), or liquid droplet microcratering (inadequate bumper thickness). Estimates of required bumper mass are given for a specific example.     

CAVITY MODELS FOR SOLID AND HOLLOW PROJECTILES

Two analytical models for the crater size generated by long-rod and thick-walled tube projectiles are presented. The first is based on energy; in a steady-state penetration, the kinetic energy loss of a projectile is related to the total energy deposited in the target. This simple approach provides an upper bound for the crater size. The second approach is based on the observation that two mechanisms are involved in cavity growth due to long projectiles: flow of projectile erosion products, which exerts radial stress on the target and opens a cavity, and radial momentum of the target as it flows around the projectile nose (cavitation). This analysis includes the centrifugal force exerted by the projectile, radial momentum of the target, and the strength of the target. Thus, it can estimate the extent of cavity growth due to projectile mushrooming, which cannot be predicted by other analyses. This model is shown to be in good agreement with experimental data.     

弹丸引信系统膛内冲击振动的研究

本文首先用质量缩聚法建立起弹引系统的初步数学模型,然后对弹引系统进行模态分析实验,获得系统的一些精确模态参数,再利用这些精确的模态参数对理论上建立的系统模型进行修正,以提高系统振动模型的准确性。最后以弹底压力为弹引系统振动模型的输入,求解出系统引信内传爆管装置处的加速度响应。     

真空伏辊空气动力性噪声实验研究

真空伏辊空气动力性噪声是造纸机的主噪声源。本文设计了真空伏辊实验模拟装置,并在其基础上通过实验研究,提出降低真空伏辊空气动力性噪声的方法。     

超空泡射弹尾拍结构动力学响应分析

超空泡射弹在运动过程中存在尾拍现象,导致结构发生振动,影响射弹的弹道稳定性,降低射弹结构的可靠性。该文建立了射弹无约束动力学方程,使用有限元法求解得到了超空泡射弹在尾拍载荷作用下的动力学响应,并对射弹的加固模型进行了分析,给出了环状加强筋个数、直径以及间距对降低射弹振幅效果的影响。研究结果表明:超空泡射弹在尾拍运动过程中转动周期和幅值随加强筋个数的增大而增大;射弹头部的弹性振动幅值随加强筋个数和直径的增大而减小,振动周期亦随加强筋个数的增大而减小;加强筋距离的减小,对于降低射弹中部振幅效果明显,但对射弹头部的振动几乎没有影响。     

高能炸药驱动下弹体膨胀破碎过程试验研究

为了获得高能炸药驱动下战斗部壳体破碎机理,选取新型弹体材料30CrMnSiNi2A钢、40CrMnSiB钢以及典型弹体材料50SiMnVB钢,采用超高速摄影技术拍摄壳体静爆,获得了不同弹体材料壳体膨胀破碎过程,引入弹体径向膨胀系数,建立了考虑弹体材料性能影响的壳体径向膨胀距离随时间变化的函数关系式,并试验测定了三种材料弹体形成破片的最大初速。分析试验结果发现,新型弹体材料壳体膨胀速度和破片初速更大,相比50SiMnVB钢壳体,30CrMnSiNi2A钢和40CrMnSiB钢壳体形成破片的最大初速分别提高了19.0%和31.9%。不同合金钢材料壳体形成破片初速沿壳体轴向分布规律相同,最大初速出现在距起爆点约70%圆筒长度处。该研究结果将为杀爆战斗部壳体材料选取及设计提供参考依据。     

陶瓷金属复合靶板工程模型及耗能分析

基于实验和数值模拟,将穿甲子弹侵彻陶瓷金属复合靶板的过程分为两个阶段,分别计算弹体侵彻陶瓷面板的动能损失、粘结层及金属背板的耗能,建立了计算弹道极限的工程分析模型,其结果与实验吻合较好。基于所建立的工程模型,分析了复合靶板各组分对其抗弹性能的影响。结果表明,陶瓷/金属复合靶板的耗能机制主要是背板耗能和弹丸质量损失耗能,分别约占初始动能的60%―95%和5%―40%。     

Flutter of viscoelastic strips

Using linear model, the parametric sensitivity analysis of viscoelastic panel flutter with an arbitrary function of relaxation, is examined by the Laplace integral transform method. The critical values of free stream velocities and frequencies of vibrations are determined from the condition that the real parts of the poles of integrand must be zero, which correspond to harmonic motion. Approximate and exact values of critical speed and corresponding frequencies for a general isotropic viscoelastic constitutive relations are obtained. The solutions are analyzed for critical, subcritical and supercritical cases. It is shown that the viscoelastic flutter speed is smaller than the corresponding elastic one if elastic moduli of material is equal to the initial value of relaxation function. Influence of aerodynamical damper is studied assuming that the parameter of viscous property of material is small enough in comparison with the parameter of aerodynamical damper and vice versa. AMS subject classification: 74H10, 74H55, 74K20     

Hard projectile penetration and trajectory stability

We present a general framework to describe the dynamics of a hard projectile penetrating into a solid target. Rigid body dynamics, differential area force law and semi-empirical resistance function are used to formulate the motion of the hard projectile. The proposed model is capable of predicting the projectile trajectory under various oblique and yaw angles. Critical conditions for the occurrences of the instability and the reverse of the projectile trajectory are discussed. It was found that the relative location of mass centre of the projectile has strong influence on the control of the rotation of the projectile, and thus, the projectile stability and the change of trajectory direction. The validity of the proposed model is limited to deep penetration and when the wake separation and reattachment between projectile body and target have negligible influence on the target resistance to the projectile.