Abnormal Shape Mould Winding

为解决网格化芯模的缠绕问题,本文提出了复合材料面片缠绕机理;接着详细分析了面片缠绕过程中的芯模凹曲面上纤维滑线和架空现象,应用微分几何曲面理论和空间几何理论,提出判据及其解决方案;最后,针对飞机发动机进气道的缠绕成型,编制缠绕控制程序并进行相应的实验,验证了面片缠绕方法的可行性。     

基于非测地线理论的回转体缠绕成型的数学模型

根据非测地线缠绕的有关理论，详细分析了微机控制纤维缠绕机的丝嘴运动规律，推导出了丝嘴运动方程和芯模的转角方程，为复杂芯模的缠绕以及微机控制纤维缠绕机的推广应用奠定了基础。     

预浸带缠绕过程缠绕层温度场变化研究

为了研究工艺参数对复合材料缠绕层的温度分布的影响,采用经典热力学理论针对预浸带缠绕过程中的传热机制进行分析;基于缠绕过程中的周期性变化规律,同时以变化的旧层初始温度为传热模型的初始边界条件,构建预浸带缠绕温度分布模型,并通过Matlab编程获得一维热传递模型的精确数值解。理论分析了缠绕初始温度、缠绕速度及芯模温度对缠绕层温度变化的影响。结果表明,对缠绕层温度影响程度依次为芯模温度＞缠绕速度＞缠绕初始温度;而且无论影响参数如何变化,缠绕层的温度分布始终为内层温度较低,并随着径向位置增大,缠绕层温度也在逐渐升高,直到外层最高温度。此外,通过实验对比分析,说明该温度分布模型满足工程要求,可为缠绕工艺研究提供指导。     

国产芳纶纤维复合材料试验容器缠绕成型及其性能介绍

本文主要报导国产芳纶Ⅰ(简称F_(14)),芳纶Ⅱ(简称F_(1414))纤维复合材料缠绕成型工艺,包括φ150压力容器的芯模制作,容器缠绕成型,容器水压试验及其内器性能,并与K-49(965)型纤维复合材料缠绕的同类压力容器进行对比.     

大型等剪应力钢丝缠绕芯筒的失稳校核

 针对大型预应力钢丝缠绕芯筒在缠绕过程可能发生失稳的复杂问题,在已有的等张力钢丝缠绕结构失稳理论与公式基础上,提出了一种新的等剪应力钢丝缠绕失稳校核公式。通过545 MN、726 MN超大型等静压设备钢丝缠绕芯筒的应用算例,结合实际缠绕施工过程的测量数据,验证了所提算法的可靠性和芯筒预紧完毕后芯筒外压公式的正确性。该算法为大型等剪应力钢丝缠绕芯筒失稳校核提供了理论依据,也为超大型缠绕缸体的方案设计和结构优化创造了条件。     

圆柱形过滤器端部缠绕的堆积问题

在对圆柱形过滤器进行缠绕成型时,由于缠绕角、端部过渡长度以及芯模直径的大小等影响,过滤器端部经常出现纤维堆积的现象,导致纤维缠绕精度下降、机床运动干涉而造成材料浪费。经理论分析和仿真试验,提出了分别基于改变摩擦系数、调整轨迹跳越数和调整端部过渡段的减轻堆积的方法,最后应用该方法对航空用油过滤器进行缠绕成型试验,验证该方法的正确性和可行性。     

复合材料缠绕后置处理方法研究

利用芯模表面的离散落纱点,依据空间几何和微分几何理论,针对纤维缠绕过程提出纤维缠绕出纱点轨迹的网格后置处理方法。该方法首先通过纤维缠绕轨迹的落纱点,以及缠绕过程中等悬纱长约束条件来求取出纱点,然后通过计算相邻出纱点的各坐标差得到机床运动轨迹,最后分别通过对三通管和组合回转体的缠绕成型实验,来验证该网格后置处理方法在处理非回转体和回转体缠绕出纱点轨迹的可行性和准确性。     

圆筒纤维缠绕变张力神经网络动态控制

 缠绕张力作为纤维缠绕成型中的关键影响因素,其波动直接影响缠绕精度和制品的性能。针对缠绕张力的动态变化,且保证制品等环向残余应力,提出神经网络动态控制缠绕变张力方法。考虑芯模变形影响,基于各向异性缠绕层弹性变形及各向同性内衬厚壁筒理论,给出外压作用下缠绕层的径向应力及环向应力;在弹性范围内采用应力叠加原理建立剩余张力与缠绕张力之间的解析算法。基于制品环向残余应力叠加特点,采用给定输出层权值的神经网络算法,通过误差反向传播及放大方法,对等环向残余应力制品纤维缠绕过程中的缠绕变张力进行动态更新。仿真与实验结果表明:该控制方法对纤维缠绕变张力起到动态优化作用,可以达到预期要求,且更符合实际缠绕过程。     

带药柱缠绕复合材料工艺研究

叙述了带药柱缠绕复合材料新工艺。该工艺把药柱、发动机前封头、后封头、包覆层和绝热层组装成组合芯模，然后缠成固本燃烧燃气生器。产品质量可靠，气密性试验，抽样常温点火试验以及姿控系统单试验合格率均为１００％。     

芯模填充对铜钛复合管绕弯截面畸变和壁厚减薄作用的模拟研究

为了提高铜钛复合管绕弯成形精度,基于所建有限元模型,研究了刚性芯模参数对复合管截面畸变和壁厚减薄的影响规律,并对比了刚性芯模填充和弹性芯模填充。研究结果表明:(1)随着刚性芯棒伸出量的增大,双金属复合弯管的基、覆管截面畸变率逐渐减小,壁厚减薄率逐渐增大,最佳芯棒伸出量为7mm。(2)较之无芯模填充,采用刚性芯模填充后,截面畸变显著降低,但是壁厚减薄率增大;控制截面畸变时,一定要考虑芯模对复合管壁厚减薄率的影响,并根据实际生产要求和管材尺寸结构灵活选择填充状态。(3)弹性芯模填充时,截面畸变率沿弯曲方向的分布较之刚性芯模均匀;刚性芯模较之弹性芯模可以更好地控制复合管的截面畸变,但最大差距只有1.03%。弹性芯模较之刚性芯模可以更好地控制复合管的壁厚减薄率,最大差距为3.27%。综合考虑截面畸变和壁厚减薄,弹性芯模对双金属复合管的填充效果更好。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.