基于MOPSO的航空发动机分支管路多目标布局优化

分支管路的布局优化属于NP难问题,其多目标优化情况则更加复杂。针对航空发动机分支管路多目标敷设问题,以分支管路长度最小化、分支点数量最小化以及管路平滑度最优为优化目标,建立了基于避障Steiner树的分支管路多目标布局模型。考虑到模型的复杂性,设计基于多目标粒子群优化（Multi-objective particle swarm optimization,MOPSO）的模型求解算法。其中,以分支点数量和坐标作为决策变量;针对分支管路拓扑结构特点,提出一种分支管路平滑度计算方法,结合非支配排序和网格密度计算完成个体多目标评价;通过可视图和测地线处理约束条件;通过多目标粒子群进化计算求得Pareto解集。所建立的分支管路多目标布局模型及求解算法考虑了多端点情况、多目标优化以及避障约束。最后通过管路敷设算例验证了可行性。     

波纹管管形的优化设计

简述了波纹管结构的特点，以工程应用中最为常见的正弦波和直线波管形为例，通过采用有限元方法对各种参数下管形结构的刚度、应力情况进行分析，为对这些管形结构优化设计提供了依据。     

Turbulent flow field structure of initially asymmetric jets

The near field structure of round turbulent jets with initially asymmetric velocity distributions is investigated experimentally. Experiments are carried out using a constant temperature hot-wire anemometry system to measure streamwise velocity in the jets. The measurements are undertaken across the jet at various streamwise stations in a range starting from the jet exit plane and up to a downstream location of twelve diameters. The experimental results include the distributions of mean and instantaneous velocities, vorticity field, turbulence intensity, and the Reynolds shear stresses. The asymmetry of the jet exit plane was obtained by using circular cross-section pipes with a bend upstream of the exit. Three pipes used here include a straight pipe, and 90 and 160 degree-bend pipes. Therefore, at the upstream of the pipe exit, secondary flow through the bend and mean streamwise velocity distribution could be controlled by changing the curvature of pipes. The jets into the atmosphere have two levels of initial velocity skewness in addition to an axisymmetric jet from a straight pipe. In case of the curved pipe, a six diameter-long straight pipe section follows the bend upstream of the exit. The Reynolds number based on the exit bulk velocity is 13,400. The results indicate that the near field structure is considerably modified by the skewness of an initial mean velocity distribution. As the skewness increases, the decay rate of mean velocity at the centerline also increases.     

Experimental investigation on onset criteria of liquid/gas entrainment in the header-feeder system of CANDU

An experimental study has been performed to investigate the off-take phenomena at the header-feeder systems (horizontal header pipe with multiple feeder branch pipes) in a CANDU (CANadian Deuterium Uranium) reactor with the branch orientation varies ±36° or ±72°. In order to evaluate the applicability of the conventional correlations used in the safety analysis code, RELAP5-Mod3, the test facility is designed with the 1/2 scale of the CANDU 6. It was found that the data set for the top, bottom and side branches are in a good agreement with the correlations used. However, for the specific angled branches, ±36° and ±72°, the onsets of off-take data and quality data showed large deviation with the conventional model inside RELAP5-MOD3. Furthermore, based on the uncertainty analysis, the conventional 2.5 power law needs to be modified. The present experimental data set can be useful for the construction of the general correlation considering the arbitrary branch orientation.     

航空发动机系统复杂管路结构振动特性

针对高速运转带来的处于高温环境、狭小空间内复杂管路不平衡振动问题,开展航空发动机系统复杂管路的结构振动特性研究。从系统直管和弯管结构振动特性分析提出复杂管路结构数值建模方法,并基于航空发动机复杂管路一般具有对称的结构特点,对系统复杂管路从总体结构和径向结构角度开展振动特性分析与结构优化。分析结果表明:作为轴对称复杂管路结构,3个对称加载的总体结构呈现刚体模态,而20°的管路径向结构在基本加载下振动变形集中于异面支管,且总管增加不同载荷对其结构变形减小无正向影响,故从运行角度为狭窄空间内管路设置结构限制条件,有助于减少系统复杂管路运行故障的发生。     

Optimization studies of the ITER low field side reflectometer

Microwave reflectometry will be used on ITER to measure the electron density profile, density fluctuations due to MHD/turbulence, edge localized mode (ELM) density transients, and as an L-H transition monitor. The ITER low field side reflectometer system will measure both core and edge quantities using multiple antenna arrays spanning frequency ranges of 15-155 GHz for the O-mode system and 55-220 GHz for the X-mode system. Optimization studies using the GENRAY ray-tracing code have been done for edge and core measurements. The reflectometer launchers will utilize the HE11 mode launched from circular corrugated waveguide. The launched beams are assumed to be Gaussian with a beam waist diameter of 0.643 times the waveguide diameter. Optimum launcher size and placement are investigated by computing the antenna coupling between launchers, assuming the launched and received beams have a Gaussian beam pattern.     

气力输送过程分支管路阻力特性的研究

在水平T型分支管道中,用压缩空气对平均粒径为0.25 mm的砂石进行气力输送试验。试验结果表明,在发送压力保持不变的情况下,输送气速和分支管路流量控制阀开度差值的变化,对分支管各自的阻力特性和相互间的压差有显著影响。当输送气速下降时,两分支管相互间的压差减小,各分支管的单位长度压差在开始时逐渐减小,但当气速下降到一定程度后,单位长度压差转而增大。当分支管流量控制阀开度差值由小变大时,两分支管各自的压差曲线逐渐远离,且两分支管相互间的压差逐渐增大。     

Heat dissipation in high-power semiconductor lasers with heat pipe cooling system

This study focuses on the application of heat pipes in thermal management for high-power semiconductor lasers. The heat pipe cooling systems are used for heat dissipation in high-power semiconductor lasers. These systems are used instead of water cooling machines to realize a compact and lightweight laser module. The n-shaped heat pipe cooling system, which consists of eight 6 mm copper heat pipes with sintered powder wicks, can easily handle a heat load of up to 73 W from a single-laser unit. The fabricated U-shaped heat pipe cooling system, which consists of ten 12 mm copper heat pipes with sintered powder wicks, can easily handle a heat load of up to 300 W from five laser units. The optical power of the multi-laser module cooled by the U-shaped heat pipe cooling system reaches 210 W. These results indicate that high-power semiconductor lasers can be cooled using heat pipe cooling systems instead of water cooling machines.     

基于Creo二次开发的液压管路智能设计系统的研究与应用

针对Creo软件中的Pro/ping模块无法满足复杂液压管路设计要求这一问题,对Creo软件进行二次开发。建立了完善的管路设计资源库,以解决原模块资源库匮乏的问题。提出软硬管联合设计的理念,实现了管路路径的快速设计与灵活调整。设计了具有优先级参考功能的管件选型模块,体现了智能设计的理念,解决了报表输出时多个物料对应同一编号的问题。通过与传统设计模式进行对比测试,验证了系统的可靠性和高效性,为工程行业解决液压管路设计问题提供了新的思路和方向。     

3维管路铺设技术研究与系统开发

设计了复杂机电产品3维管路铺设系统的体系结构。提出了利用离散小球干涉检查方式探索路径控制点的方法,继而研究了空间位置规划、路径自动搜索及路径修改等管路铺设的关键技术,实现了管路的连通性、最小弯曲半径等约束检查,完成了管路的实体拆分,并以报表方式输出铺设结果。另外,为了提高铺设效率,建立了可扩充的标准连接件库。最后,给出了3维管路铺设实例,验证了该3维管路铺设系统的实用性。     

相交双管焊接坡口的数据化处理

运用空间解析几何知识建立了相交双管焊接装配时，沿径向切割的支管与非切割的主管密闭准确安装的数学模型，给出了相交双管相贯线的参数方程，导出了相交双管相贯线上各点局部二面角的计算表达式。以此为基础开发了相交双管焊接坡口的数据化处理系统。该系统可计算出相交管子焊接装配所需要的所有参数。实管切割实验表明，所切支管与主管装配准确，焊接坡口各参数完全符合AWS D1．1规范的要求。     

半自动液压弯管机及其PLC控制

介绍一种新型半自动液压弯管机,它可在手工送料和手动转角下自动弯管,实现管件同半径三维多弯.对其工作原理、液压系统和PLC控制系统等方面进行介绍,阐述了该机的性能特点,控制系统使用了工业级的可编程控制器和触摸屏,使整个系统运行更加稳定、可靠,抗干扰能力更强,故障率更低.     

An application of genetic algorithm for edge detection of molten pool in fixed pipe welding

This paper presents a study on an application of genetic algorithm (GA) for edge detection of molten pool in fixed pipe welding. As circumferential butt-welded pipes are frequently used in power stations, offshore structures, and process industries, it is important to investigate the characteristic of the welding process. In pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small-diameter pipes progresses. In order to avoid the errors and to maintain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used an omnidirectional camera to monitor backside image of molten pool. A method of optimization for image processing algorithm using GA was proposed and has been implemented into a process to recognize the edge of molten pool. The result of detection, which is back bead width, was delivered into a fuzzy inference system to control welding speed. The experimental results show the effectiveness of the control system that is confirmed by a sound weld of the experimental results.     

流场中填充吸声材料夹层板结构与声腔的耦合特性

采用等效流体模拟吸声材料,建立外部流场作用下填充吸声材料夹层板结构与封闭空间声场的声振耦合模型,应用波动分析方法研究结构的声透射性能,分析入射声波入射角和方位角、流场流速和流向、夹层板几何尺寸和声腔深度等参数对填充吸声材料夹层板结构声振耦合特性的影响。计算分析表明吸声材料提高了结构的隔声性能;结构的隔声性能随着面板厚度和夹层厚度的增加而提高,且"板-等效流体-板"共振频率向低频移动;随着入射角、方位角、马赫数和空腔深度的变化改变了结构的隔声性能,驻波衰减频率和驻波共振频率随入射角和方位角的增大向高频移动,随空腔深度的增加向低频移动,顺流入射时随马赫数的增加向低频移动,而逆流入射时则移向高频。     

Limit load analysis for the piping branch junctions under in-plane moment

An approximate analysis approach for plastic limit load of piping branch junctions, by means of the relationship of the internal force between the main and branch pipes around intersection line, is presented in this work. The approach is built on the following process: based on the external force equilibrium condition, an equation between the limit load and internal force of the branch pipe around intersection is derived firstly. And then, taking this internal force as an external force acting on the intersection of the main pipe, the approximate solution of the internal force around the intersection on the main pipe is given as a function of the limit load. Finally, referring to the von-Mises yield criterion, the limit load of component with two intersecting cylindrical shells is then obtained. In use of the proposed approach, a closed form of limit load solution for piping branch junction under in-plane moment is developed. Finite element (FE) models of the idealized piping branch junction with various diameters and wall-thickness of the main and branch pipes were analyzed by using nonlinear FE software. The limit loads from FE analysis, from the proposed solution and six experimental data of real piping branch junctions are compared. Overall good agreement between the different limit loads was observed which provides confidence in the use of the proposed formulae in practice.     

基于冗余关节机器人的插接管道焊缝扫查系统设计

针对相贯线焊缝难以检测的问题,提出了一种新型的管道插接相贯线焊缝扫查机器人系统,通过管道夹紧装置使得机器人可附着于支管上作360°圆周运动,特别是通过冗余关节的设计实现了机器人末端探测器要求的空间相贯线扫查轨迹.该系统可实现两种管道扫查方式:一种是沿不同的扫查半径做360°周向扫查;另一种方式是沿径向呈"Z"字形进行扫查.可实现支管直径为100～400mm,被扫管道直径为600～1000mm范围内的相贯线焊缝扫查.系统设计分析和控制运行结果表明:扫查的周向步进精度≤0.2mm/m,径向步进精度≤0.5mm/m,轴向步进精度≤1mm/mm.     

An experimented study on the flow characteristics in a three-dimensional cylindrical branching channel

In this paper, we report on an experimented study on incompressible Newtonian flow in a three-dimensional cylindrical branching channel. The flow configuration studied in the present investigation is such that a fully developed laminar flow enters an abruptly expanded cylinder and the flow leaves this cylinder by two identical cylindrical outlet branch pipes. Representative velocities in the flow field were recorded by LDV (Laser Doppler Velocimetry) measurements, and volume flow rate from each outlet branch pipe was measured. Flow visualization in representative symmetric planes was also carried out. Based on results of the present investigation, the flow field in the three-dimensional cylindrical branching channel was clarified within the range of laminar flow. The characteristics of the branch flow rate were obtained and showed that there exist two distinct domains of strong asymmetric flow distribution from the outlet branch pipes, depending upon Reynolds numbers. It was further observed that the flow became time periodic as the Reynolds number was increased.     

Measurement of deflections in buried flexible pipes by close range digital photogrammetry

In this study, the monitoring of the load–deflection behavior of buried flexible pipes by digital close range photogrammetry was described. Experimental investigations were performed in a test box made of steel, with a Plexiglas front wall. An online vision system with three CCD cameras was developed to measure automatically the deflections of pipes during load tests. The system can also correct image distortions caused by refraction of light rays passing through different medias. The computational approach involves first determining camera calibration parameters, then calculating of object coordinates of targets placed on pipe wall section after each load step using the results of the calibration process. In loading tests, LVDTs were also used to measure the changes in vertical diameters of the pipes. The comparison of results obtained from both measurement systems indicated that photogrammetric system is reliable and accurate to monitor deflection behavior of pipes under loading conditions.     

波纹管密封先导式安全阀

介绍了新型先导式安全阀利用波纹管对阀瓣上腔密封的特性,解决了阀门使用在高温介质中密封性差,容易产生内漏等问题。     

The effect of cracks on the limit load of pipe bends under in-plane bending: Experimental study

This paper considers the effect of defects or cracks on the collapse load of thin walled pipe-bends under in-plane bending. Experimental work is described which was carried out to establish the limit moment for bends containing both circumferential and meridional defects. The results of the collapse tests on the bends without defects were in good agreement with limit analysis predictions, modified to take account of the stiffening effect of tangent pipes. Meridional defects do not substantially reduce the limit moment of short radius bends, whereas significant reductions can occur for cracks of length greater than one pipe diameter in long radius bends. The results for bends containing circumferential cracks indicate that a significant reduction in limit moment occurs for crack lengths greater than one pipe diameter.