基于位移场的涡轮叶片模具设计中的反变形技术研究

为了提高涡轮叶片的成形质量，减少模具的修模次数，提出了一种基于反变形原理的模具优化设计方法。通过使用ProCast软件对涡轮叶片进行铸造过程仿真，利用有限元模型计算涡轮叶片的精铸位移场，建立基于位移场的反变形方法，并使用该方法对模具进行优化设计，经涡轮叶片模具设计仿真试验验证，所采用的方法取得了良好的效果，可初步应用于模具的优化设计中。     

基于位移场的涡轮叶片模具设计中的反变形技术研究

为了提高涡轮叶片的成形质量,减少模具的修模次数,提出了一种基于反变形原理的模具优化设计方法。通过使用ProCast软件对涡轮叶片进行铸造过程仿真,利用有限元模型计算涡轮叶片的精铸位移场,建立基于位移场的反变形方法,并使用该方法对模具进行优化设计,经涡轮叶片模具设计仿真试验验证,所采用的方法取得了良好的效果,可初步应用于模具的优化设计中。     

涡轮叶片形状检测中的模型配准控制点集选取

叶片模型的配准定位是叶片形状检测与分析的一个核心环节。为解决基于迭代最近点方法的叶片密集测量数据与其CAD模型的可靠配准问题,提出一种基于CAD模型的配准控制点集选取方法。结合模型配准可靠性分析技术,预先在叶片CAD模型规划出配准基准点集;通过测量数据与配准基准点集的配准运算,把配准基准点集映射到叶片测量数据上,获取测量模型上对应的配准控制点集;滤除其中可能降低模型配准精度的坏点,得到最终的叶片模型配准控制点集。进行基于仿真与实测数据的叶片模型配准试验及对比分析,总结出一些可用于指导叶片模型配准控制点集选取的策略。结果表明,所提出的叶片模型配准控制点集选取方法是可行的。     

高温涡轮叶片变形重构研究

高温涡轮叶片在整个设备可靠运行的过程中起着至关重要的作用,因此在工作状态下监测高温涡轮叶片的变形非常重要。这里将高温涡轮叶片简化为二维梁结构,分析了涡轮叶片的主要变形形式,通过变形重构算法建立了应变-变形的数学模型,搭建了基于FBG的高温涡轮叶片变形检测实验系统,在常温和500℃高温下对叶片施加不同类型的负载,利用光纤光栅传感器检测测点应变并重构叶片的变形;实验结果与ANSYS仿真结果及位移传感器测得的变形结果吻合程度较好,证明了该测量方法和变形重构算法的有效性。     

精铸涡轮叶片的误差分析技术

针对精铸涡轮叶片的检测和模具型腔设计中存在的精度控制问题,运用配准技术来进行误差分析,分别以形心、收缩中心、中心轴线点为特征点,运用CAD模型引导的最临近点迭代ICP(iterative closet point)配准方法,将叶片实际测量数据和CAD模型进行配准。对比配准结果,得到了精铸过程中误差分布,并通过分析叶片的变形情况,得出以形心为特征点时,型面重合度最大,配准效果最好,为叶片精铸模具的型腔设计提供了量化的参考依据。     

基于中弧线的空心涡轮叶片壁厚计算方法研究

针对高精度复杂空心涡轮叶片壁厚测量问题,提出了一种基于中弧线的壁厚计算方法。通过对空心叶片CT切片数据的处理,建立了相应的点云数据测量模型,并与叶片CAD模型进行配准,实现了各截面数据点的提取与拟合,从而计算出了中弧线;在此基础上,运用UG二次开发平台求出了叶片各点的壁厚。实测结果表明:通过该方法能够精确计算复杂空心涡轮叶片的壁厚,提高空心叶片壁厚精度及其可靠性。     

陶瓷型芯结构对涡轮叶片型面精度影响的仿真研究

在精密铸造成形过程中,陶芯对凝固收缩存在机械阻力,因此,陶瓷型芯的复杂结构对空心涡轮叶片型面尺寸精度有较大的影响。基于精铸数值模拟方法,分析了陶瓷型芯结构对叶片变形影响的规律。借助ProCAST软件对空心涡轮叶片的凝固过程进行仿真,获得变形位移场。分析了由三种不同结构陶瓷型芯所得的位移场,采用位移量变形趋势图对比的方式揭示了陶瓷型芯结构对叶片变形影响的规律,为模具优化提供量化依据。     

一种区域公差约束的叶片模型配准方法

针对航空发动机涡轮叶片几何形状检测中的模型配准定位问题,依据叶片型面区域公差设计的特点,提出一种区域公差约束的叶片模型配准方法,尽可能把模型配准控制点集约束在公差带以内。在迭代最近点配准方法的目标函数的基础上,附加区域公差约束条件,建立区域公差约束的叶片模型配准目标函数,并给出了基于遗传算法叶片模型约束配准求解方法。使用叶片的仿真与实测数据进行了模型配准实验,结果表明,所提出的方法能显著减少配准控制点集的超差点数目。     

椭圆匹配法在空心涡轮叶片3D配准中的应用

在三维CT设备对空心涡轮叶片进行无损检测时会存在定位偏差问题 ,三维数字样品图像模型的配准是关键的一步。本文首先对CT切片图像提取轮廓点 ,然后借助转动惯量计算惯量椭圆并进一步对惯量椭圆匹配以获得所需的几何变换的参数 ,从而实现CT图像与理论模型之间的配准。仿真结果表明 :此方法用于空心涡轮叶片 3 D配准可取得满意效果     

基于截面特征约束的涡轮叶片重构技术

为了解决涡轮叶片在其产品改型、气动优化、叶片修复等实际工程问题需要建立实物数字化模型的问题,采用截面特征技术与二维草图约束功能相结合应用于模型重构。针对涡轮叶片几何特征和气动设计要求,将涡轮叶片点云切片截面曲线分层表达为曲线元并分段进行差值拟合,基于二维草图约束技术对截面曲线进行几何特征约束,构造出满足约束条件与数据点逼近的最优曲线并放样生成曲面。结果表明,基于截面特征的反求工程技术与二维草图曲线约束优化技术相结合,可以快速、准确构造出复杂曲面,提高了逆向建模的效率,为快速重构模型提供了一种方法。     

Elastic deformation of a fixture and turbine blades system based on finite element analysis

Finite element analysis (FEA) has been used to recapitulate the interactions between fixtures and components over the last decade. Most of the researches were focussed on the 3-2-1 fixture for components with regular geometry using point-to-point contact elements, where the fixture element is represented by a point-contacting component. Due to predicable behaviour of the fixture–component pair, such a point-to-point contact representation may be sufficient. However, when components with complex geometry, e.g. B-spline surfaces, which are widely used in the automotive and aero-engine industries, are of interest, the point-to-point method can no longer be satisfactory. This paper proposes a method of FEA on a system of a fixture and turbine blades by considering the complex contact geometry and complicated contact status of fixture–component pairs using surface-to-surface contact elements. A complete procedure of FEA modelling including geometry simplification, contact modelling, stiffness of locators, mesh generation, boundary condition and loading sequence is explained in detail. Having verified the FEA prediction of the elastic deformation with the displacement of the workpiece measured by coordinate measurement machines (CMMs), the influential factors of deformation, such as friction and machining directions, are analysed.     

水轮机叶片坑内修复机器人修磨方式研究

介绍了一款自主设计的可进行水轮机叶片坑内高效率修复的磁吸附爬壁式机器人.经过实验验证得出:普通铣削的切削力、冲击过大不能用于水轮机叶片坑内修复,但可以进一步研究高速铣削的应用可行性.磨削可用于坑内修复,进一步实验证明采用缓进深切磨削修磨焊缝时效率高,磨削力较小,满足机器人的设计承载要求,可用于水轮机叶片坑内修复.     

Automatic inspection of turbine blades using a 3-axis CMM together with a 2-axis dividing head

Turbine blades are widely used in turbo-engines and generators. The complex geometry of turbine blades and the limited space between two adjacent blades cause difficulties in both machining and inspection. This paper is focused on the use of a 3-axis coordinate measurement machine (CMM), together with a dividing head with two rotational axes, to undertake the task of precision inspection of turbine blades that surround the periphery of an axial wheel. Based on the geometrical relationship between the probe stylus and the turbine blades, a methodology is proposed to find the angle of rotation of the axial wheel when a collision is likely to occur between them. Other issues related to system implementation are also discussed in this paper, including: (1) Data transformation from the turbine blade’s geometric model to the CMM control codes, (2) Planning of the traveling paths of the stylus, and (3) Analysis of the measured data.     

大型风力机叶片的耦合优化方法

为了降低兆瓦级风力机叶片的制造成本,通过耦合叶素动量理论与复合材料欧拉伯努利梁强度设计理论,综合考虑风能效率和成本,以叶片的风能效率成本最小化为优化目标,提出了大型风力发电机叶片的多学科优化设计方法。并基于该方法,对某50 m风力机叶片进行了优化设计。研究结果表明,该方法能够找到风能效率与成本的平衡设计点,叶片风能效率成本比传统设计方法设计的叶片减少了8.84%。     

三维涡轮叶片交互式造型程序设计

介绍和讨论了十二参数法、预置曲率法、和Bezier曲线法三种典型的涡轮叶片解析造型方法的原理和步骤,以及叶片的三维复杂成型方法。并且编制了基于以上方法的三维涡轮叶片造型交互式程序,以设计实例阐述了叶片造型原理和步骤、交互式程序的编制方法和功能。分析和讨论说明：该程序便捷、高效、可靠,具有强的干涉性和交互性,能够满足复杂的涡轮三维弯扭掠叶片造型工程实用需要。     

Development of a water droplet erosion model for large steam turbine blades

Water droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious operational problems such as performance degradation and reduction of service life. A new erosion model has been developed in the present study for the prediction of water droplet erosion of rotor blades operated in wet steam conditions. The major four erosion parameter ; impact velocity, impacting droplet flow rate, droplet size and hardness of target are involved in the model so that it can also be used for engineering purpose at the design stage of rotor blades. Comparison of the predicted erosion rate with the measured data obtained from the practical steam turbine operated for more than 90.000 hours shows good agreement.     

基于ANSYS的某型航空发动机涡轮叶片的振动特性分析

以某型航空发动机的高压涡轮叶片为研究对象,采用Solidworks软件建立其三维实体模型,基于有限元分析软件ANSYS对其进行振动特性分析,得出叶片的振动频率特性和前六阶振动模态特性。仿真结果对涡轮叶片的设计和改进具有一定的指导意义。     

The use of displacement sensitive organic field effect transistor for telemetry system applications

The thin films of the organic semiconductor material Copper Phthalocyanine (CuPc) and metal Aluminum (Al) were deposited in a sequence by vacuum thermal evaporation technique on glass substrate with Silver (Ag) as source and drain electrodes. The effect of displacement on properties of the fabricated Organic Field Effect Transistor (OFET) was investigated. It was observed that the drain-source resistance of the OFET decreased eight times with the increase of the displacement in the range from 0 to 550 μm. The sensor was then connected to square wave oscillator. It was found that with the increase of displacement, the oscillator’s frequency also increased in the range of 3.3-11.0 kHz. This Displacement Sensitive Field Effect Transistor (DSFET) controlled oscillator can be used for short-range and long-range telemetry systems in the environmental monitoring and assessment. Moreover it has industrial applications too.