TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE (Ⅱ)- TOPOLOGICAL FLOW PATTERN AND VORTEX STRUCTURE IN THE TRANSVERSE SECTION OF A BLADE CASCADE

By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.

AN APPLICATION OF TOPOLOGICAL METHOD TO ANALYSING THE THREE-DIMENSIONAL FLOW IN CASCADES(Ⅱ)-TOPOLOGICAL ANALYSIS ON THE VECTOR FIELD PATTERNS OF SKINFRICTIONS AND SECTION STREAMLINES

With an application of topological analysis,in this paper the skin-friction line patterns on compressor and turbine cascade surfaces are depicted and the streamline patterns of the secondary flow fields in the cross-section of a curved pipe and a turbine cascade are drawn under given conditions.In addition the structures of vortices within three-dimensional viscous flow fields in cascades are analysed.

TOPOLOGICAL STRUCTURES OF VORTEX AND HELICITY ANALYSIS

The topological structures of the vortex filaments and vortex tubes with an exact solution of a straight spiral vortex tube are discussed. It is found that there are some confusions about the calculation of the helicity of a knotted vortex filament and some linked vortex filaments by using different methods. How to unify these methods is explained and the right results are given. (Edited author abstract) 5 Refs.

Full-Scale Isogeometric Topology Optimization of Cellular Structures Based on Kirchhoff-Love Shells

Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight ratio.In this paper,a full-scale isogeometric topology optimization(ITO)method based on Kirchhoff-Love shells for designing cellular tshin-shell structures with excellent damage tolerance ability is proposed.This method utilizes high-order continuous nonuniform rational B-splines(NURBS)as basis functions for Kirchhoff-Love shell elements.The geometric and analysis models of thin shells are unified by isogeometric analysis(IGA)to avoid geometric approximation error and improve computational accuracy.The topological configurations of thin-shell structures are described by constructing the effective density field on the controlmesh.Local volume constraints are imposed in the proximity of each control point to obtain bone-like cellular structures.To facilitate numerical implementation,the p-norm function is used to aggregate local volume constraints into an equivalent global constraint.Several numerical examples are provided to demonstrate the effectiveness of the proposed method.After simulation and comparative analysis,the results indicate that the cellular thin-shell structures optimized by the proposed method exhibit great load-carrying behavior and high damage robustness.

Topological Structure of Vortex Solution in Jackiw-Pi Model

By using φ-mapping method,we discuss the topological structure of the self-duality solution in Jackiw-Pimodel in terms of gauge potential decomposition.We set up relationship between Chern-Simons vortex solution andtopological number,which is determined by Hopf index and Brouwer degree.We also give the quantization of flux inthis ease.Then,we study the angular momentum of the vortex,which can be expressed in terms of,the flux.

Study on topology and vortex structure in a diffusion cascade

To further make clear vortex structures in diffusion cascades so as to help understand the mechanisms of vortex affecting loss production, the emergence, evolution and development of secondary flow vortexes, including horse shoe vortex, passage vortex and corner vortex and so on, were discussed mainly through using the topological analysis method and numerical calculation. The concept of a three-dimensional dividing surface between the low energy flow zone and the exterior flow zone was presented. The results show that concentrated shed vortex is located outside the dividing surface (in the outer flow zone) and horse shoe vortex, passage vortex and corner vortex are inside the dividing surface (in the low energy flow zone). Dissipation function is used to measure loss production instead of using entropy production. The results about loss analysis indicate that vortex motion directly causes loss production, namely, peak value of loss is generally located around the core of vortex and that maximal loss happens around the dividing surface other than in the low energy flow zone.

THE SATELLITE STRUCTURE TOPOLOGY OPTIMIZATION BASED ON HOMOGENIZATION METHOD AND ITS SIZE SENSITIVITY ANALYSIS

With the development of satellite structure technology, more and more design parameters will affect its structural performance. It is desirable to obtain an optimal structure design with a minimum weight, including optimal configuration and sizes. The present paper aims to describe an optimization analysis for a satellite structure, including topology optimization and size optimization. Based on the homogenization method, the topology optimization is carried out for the main supporting frame of service module under given constraints and load conditions, and then the sensitivity analysis is made of 15 structural size parameters of the whole satellite and the optimal sizes are obtained. The numerical result shows that the present optimization design method is very effective.

M-P INVERSE TOPOLOGICAL VARIATION METHODOF FINITE ELEMENT STRUCTURES

Using Moore-Penrose inverse theory, a set of formulations for calculating the static responses of a changed finite element structure are given in this paper. Using these formulations by structural analysis may eliminate the need of assembling the stiffness matrix and solving a set of simultaneous equations.

基于并行拓扑优化的假体股骨柄设计

与股骨接触的假体柄是人工髋关节的主要部件,在全髋置换手术中起着重要作用。采用变密度固体各向同性材料惩罚(Solid Isotropic Material with Penalization,SIMP)拓扑优化方法和多尺度的并行拓扑优化方法,分别得到A型和B型两种股骨柄结构,并将股骨柄结构柔度变化幅度作为对比指标,比较了两种股骨柄对载荷方向变化的敏感度。利用有限元方法对A型股骨柄和B型股骨柄进行多工况下所对应股骨的应力分析。研究结果表明,在3种工况下,A型股骨柄和B型股骨柄对股骨的平均应力分别为14.80、22.55、16.94 MPa和10.89、20.92、16.50 MPa。对B型股骨柄进行压力加载试验,试验结果表明,在内侧测点,试验的应变值与仿真值的平均误差为-1682με,平均相对误差为20.3%;在外侧测点,试验的应变值与仿真值的平均误差为1281με,平均相对误差为19.5%。该方法为股骨假体柄结构的可靠性设计提供了有效参考。

一种新型二级凸轮式分度机构动力学仿真

针对一种新型二级凸轮式分度机构的拓扑结构特点,在ADAMS软件环境下建立了机构动力学模型,分析机构的输出响应。在此基础上,研究了转速、惯性负载及针齿分度圆半径等因素对整机动态性能的影响规律。此外,分析了传动构件的针齿强度。结果表明:机构输出轴角速度值随着转速的提高而大幅度增加,随着针齿分度圆半径的增大而减小,其波动幅值随负载的增大而明显减小。机构分度期内针齿与凸轮间的动态啮合力显著波动,上述研究成果可为该类分度机构的工况参数选择原则提供一定的参考。

Numerical Study of Co-flow Jet Control on Corner Separation in Compressor Cascade

The design objectives of modern aircraft engines include high load capacity,efficiency,and stability.With increasing loads,the phenomenon of corner separation in compressors intensifies,affecting engine performance and stability.Therefore,the adoption of appropriate flow control technology holds significant academic and engineering significance.This study employs the Reynolds-averaged Navier-Stokes(RANS)method to investigate the effects and mechanisms of active/passive Co-flow Jet(CFJ)control,implemented by introducing full-height and partial height jet slots between the suction surface and end wall of a compressor cascade.The results indicate that passive CFJ control significantly reduces the impact of corner separation at small incidence,with partial-height control further enhancing the effectiveness.The introduction of active CFJ enables separation control at large incidence,improving blade performance under different operating conditions.Active control achieves this by reducing the scale of corner separation vortices,effectively reducing the size of the separation region and enhancing blade performance.

一种基于图论理论的大尺度连续变形机构构型综合分析方法

针对航空航天领域大尺度连续变形机构构型问题,提出了一种基于图论理论的大尺度连续变形机构构型综合分析方法。首先,分析了大尺度连续变形机构的组成与基本功能,获得了满足机构拓扑结构、约束条件的要求,对变形机构运动链进行了分析,得到了符合条件的运动链,并对其进行了数学描述;其次,选择并分析了运动链的拓扑对称性,利用特征数组的方法得到了判别矩阵,对运动链进行了同构判别,从而得到了可行的多种运动链形式;再次,建立了各运动链的拓扑图,通过筛选得到了最终的拓扑图,去掉该拓扑图的各个构件,得到了拓扑变换子图和相对应的邻接矩阵,对拓扑图进行了同构判别,再通过改变机架与移动副的位置得到了满足要求的12种构型,画出了其相应的机构拓扑图和机构简图;最后,考虑了大尺度连续变形机构的整体稳定性,避免了尺寸过大等因素,对大尺度变形机构进行了构型优选,得到了符合要求的多种新构型。研究结果表明:该方法能够将大尺度连续变形机构抽象为图形式,获得了22种构型,可根据机构变形要求的不同,改变优选依据,从而得到符合不同要求的构型。

海上移动平台直升机甲板圆管支撑结构安全评估

圆管支撑结构是海上移动式平台直升机甲板设计的重要部分,由于海上恶劣的风浪环境,使结构整体受风载荷的影响较大.现有直升机甲板圆管支撑结构的安全评估内容主要集中于圆管的静强度分析,缺乏风振响应分析,文中以海洋石油163平台直升机甲板为例,研究圆管支撑结构的静力和动力载荷输入,通过有限元强度分析和理论经验公式计算对比静力、风载荷作用下直升机甲板圆管支撑结构的受力情况,考虑风振涡激效应的准静态分析,在此基础上提出了直升机甲板圆管支撑结构的安全评估方法,探究了风载荷对结构整体安全的影响.

公共汽电车复杂网络模型构建与特性分析——以淄博市为例

研究公共汽电车网络特性对于合理优化线路及站点布局具有重要作用。基于复杂网络理论,使用L空间、P空间和R空间三种建模方法,分别建立公共汽电车加权网络模型,并利用Gephi软件分析网络的节点度、平均路径长度、聚类系数等静态拓扑参数。进而对淄博市公共汽电车网络进行实例分析,并与不同规模城市进行对比。研究结果显示,淄博市市区公共汽电车站点网络的度分布符合指数分布,不具有明显的无标度特性,公共汽电车换乘网络和线路网络具有明显小世界特性。居民乘坐公共汽电车出行一次,平均需要经过13.77个站点并换乘1.32次,基本可以满足当前出行需求,但是与国家公交都市建设示范城市相比仍然存在邻近站点之间连接线路不足、具有换乘功能的站点较少、网络稳定性差等问题。

成组立模成型机模板结构优化设计研究

混凝土预制构件成组立模成型机(简称成组立模)是一种新型的生产混凝土预制构件的设备。为了提高成组立模台面的振动效果和承载能力,本研究以成组立模模板结构为研究对象,提出了一种拓扑优化新兴设计与响应面法结合的优化设计理论。首先,基于变密度法对成组立模模板结构加强筋布局进行拓扑优化设计,得到了加强筋最佳的材料分布形式,以此对成组立模模板结构进行了结构优化设计。为得到最佳的加强筋设计参数,采用中心组合试验设计,建立模板结构最大位移、最大等效应力的响应面模型。利用多目标遗传算法对响应面模型进行优化求解,得出加强筋各参数最优的组合方案。有限元分析结果表明:与初始方案相比,优化设计方案提高了台面的刚度和强度,同时改善了模板结构的振动特性,并提高了混凝土预制构件的成型质量。该研究为进一步推进成组立模的研究提供了理论指导。

微小口径涡街流量计设计与测量特性研究

涡街流量计是基于流体振荡原理对流量进行测量的流量计,但在低流速下输出的信号很微弱,在实际测量过程中会叠加各种现场产生的噪音。并且目前工业上使用小口径涡街流量计在小流量工况下存在测量局限性,一般最小口径仅到DN15。针对目前涡街流量计存在的问题对DN10及以下的微小口径涡街流量计结构及参数进行研究,以满足工业上的测量新需求。基于模拟仿真计算平台,建立不同尺寸参数的微小口径涡街流量计数值计算模型并进行仿真计算,提出优化的涡街流量计结构尺寸。通过对不同压力监测点的压力波动强度及频率的研究,分析传感器的最佳布置位置。最后以电磁流量计为标准表对所研制的微小口径涡街流量计在微量程段进行了测试,对该被检流量计的误差、精度等参数进行实验,同时对雷诺数与斯特劳哈尔数之间的关系及仪表系数进行分析,结果表明,仿真所获的测量特性与实验测得的特性具有较好的一致性,且该微小口径涡街流量计相对误差优于0.5%,重复性等指标能够满足微量程段内的测量标准。

基于马蹄涡前缘吸气控制的压气机叶栅流动机理

为探究从源头抑制角区分离的流动控制方法,采用数值模拟方法,以NACA65叶栅为研究对象,利用叶栅前缘端壁吸气技术控制马蹄涡,结合拓扑分析对叶栅通道内的三维流动结构进行精确重构,以研究前缘端壁吸气控制马蹄涡进而改善叶栅通道流场结构的机理。结果表明:叶栅前缘端壁吸气技术可以有效推迟马蹄涡形成并削弱其强度,同时在吸气狭缝末端形成一对反旋流向涡对,在向下游发展过程中与通道涡相互作用;前缘端壁吸气通过控制马蹄涡,降低端壁边界层厚度,叶栅前缘通道涡发展受限,由回流组成的叶表分离被抑制;前缘及压力面侧吸气(EPS)直接作用于马蹄涡压力面分支,通道涡强度进一步被削弱,角区分离模式由闭式分离转为不完全闭式分离。最后,对比最优吸气系数下不同方案出口总压损失,发现当吸气量为进口质量流量的0.2%时,EPS方案出口截面总压损失降低5.8%;并且通过调整吸气系数,可以获得较好的变工况控制性能。

基于现有结构扩容改造泵房的优化设计研究

受限于海塘管理规定等因素,邻江雨水泵房扩容仅能依托现有结构及穿堤管线。为充分挖掘泵房排水潜能、确保排水设施安全稳定运行,以上海罗泾港区雨水泵房的扩容改造设计为例,利用CFD软件对泵房进水池流态进行仿真模拟,分析进水流量增大对整体流态、典型截面速度分布的影响,提出吸入口底部增设防旋板的优化方案,并对流态改善效果进行验证。结果表明,泵房能力扩容增加了底部漩涡形成风险,易造成泵组偏心振动;增设防旋板后水泵进水口流态得到明显改善,有利于保障和改善泵组运行稳定性,推动实现排水能力最大化提升。可为泵房扩容改造工程优化设计提供参考。

散货船顶边舱横隔板的拓扑优化设计

针对散货船顶边舱横隔板的设计主要靠母型船和工程师经验进行,以横隔板重量最轻为目标,参照原始设计的应力结果进行基于应力约束的拓扑优化。基于原始设计方案,去除顶边舱横隔板上的开孔面板、防倾肘板和屈曲筋,对结构进行细化后获得响应工况的应力作为拓扑优化的应力约束。分别对单个横隔板进行拓扑优化和对货舱内所有横隔板进行拓扑优化。基于拓扑优化结果,设计新的横隔板开孔方式并进行详细设计,并基于三舱段有限元计算对优化设计进行粗网格和细化分析校核。优化后的构型相对原始设计能获得更轻便的重量和更小的应力结果。本文的研究可以为散货船的拓扑优化、顶边舱横隔板的设计提供参考。

基于拓扑分析的断层连通性定量评价及其油气地质意义——以四川盆地南部H井区为例

受多期次构造叠加改造作用影响,四川盆地南部地区(以下简称川南地区)深层页岩气储层中发育大量的中小尺度断层,定量评价断层网络结构和平面连通性对川南地区深层页岩气的勘探开发具有重要意义。为此,以该地区H井区为例,在三维地震精细刻画H井区深层页岩储层的中小尺度断层的基础上,基于拓扑学理论开展了该井区页岩储层断层网络拓扑结构分析和断层平面连通性评价,并结合已有页岩气井测试产气量进行关联性分析,定量评价了断层网络拓扑结构和平面连通性对页岩气富集的控制作用。研究结果表明:(1)断层节点和分支在空间上具有明显的差异性分布特征,且与构造走向具有较高的吻合度,呈北东—南西向条带状展布,并集中分布于3个狭长背斜带,3个向斜区分布较少。(2)不同构造部位的断层平面连通程度存在显著差异,背斜区平面连通性普遍较好,向斜区平面连通性较差;西部背斜带北段连通性最好,东部背斜带连通性次之,中部背斜带连通性最差;东部背斜带北段连通性较好,南段较差。(3)页岩气测试产量与断层平面连通性之间具有显著的相关性,随着断层平面连通性的增强,页岩气测试产量呈先升高后降低的趋势,反映连通性高值区和低值区均不利于页岩气富集。结论认为,该认识对中小断层连通性评价具有重要价值,也对深层页岩气的勘探开发有较高的实用价值。