汽轮机叶片预铣汽道夹具

如图1所示熏在叶片加工过程中汽道的加工是最关键的一步,其型线的好坏直接影响气流的运动。从目前叶片加工的情况看,国内外全部采用数控机床加工汽道(也就是内背弧型线)。汽道预铣通常没有通用夹具,而需要根据叶片规格的不同自行设计。为此,我们设计了一种专用夹具,如图2所示。     

叶身型面拼接处理的理论及方法的研究

根据转子叶片的特殊要求,本文着重讨论了叶身型面拼接处理的理论及方法,这些方法已在工程实际中得到应用。     

面向扭曲叶片修复的曲面重构技术研究

针对修复和再制造复杂型面零件(例如:扭曲涡轮叶片)时,因原始曲面模型丢失或CAD零件图纸属其他公司的技术专利,从而无法获取精确CAD曲面模型的难题,开展了对扭曲涡轮叶片曲面重构技术的研究。将分层扫描得到的涡轮叶片测量点以基圆切点为基准进行分段处理,通过分段精密拟合曲线,再从每一段曲线上取得相同数量的点作为新的测量点,以解决各个层次上对应分段的初始测量点数目不等的问题。然后反求曲面控制点,用非均匀B样条方法得到扭曲涡轮叶片的曲面模型。借助Imageware软件对拟合得到的曲面模型进行误差分析,涡轮叶片曲面模型的平均误差被控制在可接受的范围内。     

汽轮机叶片汽道背弧夹具的改进设计

针对原使用的汽轮机叶片汽道背弧夹具存在的问题,设计了一种可用于多种型号叶片正反向汽道背弧加工的夹具。其正反向调换不用拆装夹具,调整斜度垫块角度即可实现正反向加工。     

UG环境中汽轮机叶片汽道建模方法

介绍了采用UG生成汽轮机汽道时叶片汽道型线的特点和叶片型线分类,分别介绍了数据点成型和圆弧线成型的建模方法。     

涡扇叶片在机测量自适应采样方法

涡扇叶片的加工和检测精度直接影响到涡扇的结构强度和气动性能。为提高叶片的在机测量精度和效率,提出一种基于弯矩理论的自适应曲面采样方法,以解决叶片曲面在前缘和后缘位置处曲率急剧变化以及轮廓面的全局采样问题。根据曲面的几何特征变化,自适应确定检测点的分布密度和数量。仿真和在机测量实验验证了该方法的有效性和可行性。通过与双向等参数法、改进的分区等参数法和Hammersley序列法的采样结果对比表明,基于弯矩理论的自适应采样方法实现了对采样点位置及数量的微细精准调整,采样误差小,重构表面精度高,满足在机测量对时间和精度的要求。     

基于SolidWorks的汽轮机扭曲叶片造型研究

探讨了用SolidWorks软件对汽轮机扭曲叶片实体造型的方法,采用非均匀有理B样条曲线对叶片特征截面型线进行处理,并指出了造型过程中的难点和关键点问题,在大扭曲度长叶片的实体造型过程中如何选用引导线和中心线使各特征截面经放样后成为光滑曲面.以某1029mm叶片造型为例,验证了该方法的可行性.     

汽轮机叶片汽道加工中受力及变形分析

汽轮机叶片汽道加工变形是影响加工质量的关键。为了提高汽轮机叶片在加工过程中的质量,减小其在加工过程中的形位误差,在各切削力模型的基础上研究了球头铣刀在出汽边铣削中的几何加工特征,构建铣削力模型,分析了叶片汽道加工过程中的受力和变形。结合汽轮机中压缸第二级动叶片结构参数,采用材料力学理论分析法,构建了汽轮机动叶片汽道加工中的力学模型,并对叶片汽道加工中弯曲与扭转变形进行分析,得出影响叶片加工质量的因素,为后续的叶片夹具设计提供理论依据。     

基于NURBS的水力机械叶片表面造型研究

论述了在已知叶片轴面截线图的情况下,采用B样条插值理论,求出叶片表面控制点,然后利用非均匀有理B样条方法实现叶片表面的数值化。同时可采用交互方式对叶片表面控制点或其权因子进行修改,构造出逼真的叶片,增强了叶片计算机辅助设计系统的交互设计能力;对改进叶片的设计方法和提高其设计质量具有重要意义。     

基于等几何分析的结构形状优化设计研究

等几何分析方法是近年来发展起来的一种新型数值方法,具有几何精确描述、多种网格细化方法和稳定的高阶连续协调单元等特点。本文结合该方法建立了结构优化的数学模型,通过工程实例考察了该方法应用于结构形状优化设计的有效性,结果表明基于等几何分析的结构形状优化是可行的,对克服形状优化中边界可动、网格扭曲和重建等难题提供了有力的支持,为产品设计、分析和优化过程的集成统一提供了新的选择,供工程技术人员参考。     

A study on an axial-type 2-D turbine blade shape for reducing the blade profile loss

Losses on the turbine consist of the mechanical loss, tip clearance loss, secondary flow loss and blade profile loss etc.,. More than 60 % of total losses on the turbine is generated by the two latter loss mechanisms. These losses are directly related with the reduction of turbine efficiency. In order to provide a new design methodology for reducing losses and increasing turbine efficiency, a two-dimensional axial-type turbine blade shape is modified by the optimization process with two-dimensional compressible flow analysis codes, which are validated by the experimental results on the VKI turbine blade. A turbine blade profile is selected at the mean radius of turbine rotor using on a heavy duty gas turbine, and optimized at the operating condition. Shape parameters, which are employed to change the blade shape, are applied as design variables in the optimization process. Aerodynamic, mechanical and geometric constraints are imposed to ensure that the optimized profile meets all engineering restrict conditions. The objective function is the pitchwise area averaged total pressure at the 30 % axial chord downstream from the trailing edge. 13 design variables are chosen for blade shape modification. A 10.8 % reduction of total pressure loss on the turbine rotor is achieved by this process, which is same as a more than 1 % total-to-total efficiency increase. The computed results are compared with those using 11 design variables, and show that optimized results depend heavily on the accuracy of blade design.     

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.     

UG平台下涡轮叶片曲面造型的一个处理技巧

介绍利用UG软件对涡轮叶片关键部位的造型过程中,一处缺陷的处理技巧.该方法源于渐进的设计思想,明显地抑制了曲面的皱褶.     

汽轮机叶片并联抛光机系统的研究

汽轮机叶片抛光采用人工抛光方法.基于并联机床的设计理论和发展现状,研究开发一种自动抛光的方法即采用并联机床实现叶片的抛光.在UG环境下完成叶片造型和并联机床的建模和抛光仿真.为今后实现叶片抛光自动化奠定了基础.     

An experimental study of the performance characteristics with four different rotor blade shapes on a small mixed-type turbine

A small mixed-type turbine with a diameter of 19.9 mm has been substituted for a rotational part of pencil-type air tool. Usually, a vane-type rotor is applied to the rotational part of the air tool. However, the vane-type rotor has some problems, such as friction, abrasion, and necessity of accurate assembly etc.,. These problems make the life time of the vane-type air tool short, but air tools operated by mixed-type turbines are free of friction and abrasion because the turbine rotor dose not contact with the casing. Moreover, it is assembled easily because of no axis offset. These characteristics are merits for using air tools, but loss of power is inevitable on a non-contacting type rotor due to flow loss, tip clearance loss, and profile loss etc.,. In this study, four different rotors are tested, and their characteristics are investigated by measuring the specific output power. Additionally, optimum nozzle location against the rotor is studied. Output powers are obtained through measured pressure, temperature, torque, rotational speed, and flow rate. The experimental results obtained with four different rotors show that the rotor blade shape greatly influences to the performance, and the optimum nozzlc location exists near the mid span of the rotor.     

汽轮机叶片的参数化造型及数控编程研究

为保证汽轮机叶片的加工精度和表面质量,以典型的CAD/CAM软件Pro/Engineer Widefire2.0中文版为基础,绘制了汽轮机叶片参数化设计加工的流程图;用参数化建模方法建立了叶片的三维实体模型,提出用NURBS(非均匀有理B样条)曲线拟合方法进行光顺处理,并推导出NURBS的矩阵表达式便于截面型线的拟合,进而使叶片的造型更加精确;在CAD模型的基础上,分析了叶片的加工工艺流程,并用软件的CAM功能对叶片进行数控加工仿真,生成了NC代码。叶片的参数化设计和加工处于同一软件环境下,保证了数控加工的质量和效率。     

LP compressor blade vibration characteristics at starting conditions of a 100 MW heavy-duty gas turbine

In this paper are presented the blade vibration characteristics at the starting conditions of the low pressure multistage axial compressor of heavy-duty 100 MW gas turbine. Vibration data have been collected through strain gauges during aerodynamic tests of the model compressor. The influences of operating modes at the starting conditions are investigated upon the compressor blade vibrations. The exciting mechanisms and features of blade vibrations are investigated at the surge, rotating stall, and buffeting flutter. The influences of operating modes upon blade dynamic stresses are investigated for the first and second stages. It is shown that a high dynamic stress peak of 120 MPa can occur in the first stage blades due to resonances with stall cell excitations or with inlet strut wake excitations at the stalled conditions.     

基于逆向工程的发动机叶片实体建模关键技术研究

发动机叶片是航空发动的关键零件，计算机技术的发展和功能强大的三维造型软件的出现为超薄扭曲叶片的三维实体建模带来了极大的便利。本文在逆向工程设计思想的指导下，就航空发动机叶片特有的结构和技术要求，着重讨论了叶片实体建模中型面测量数据预处理、叶身型线与进排气边过渡圆弧切点的校正和叶身B样条自由曲面拟和等关键技术问题，并对叶片型面的光顺度和平滑度进行了校验，从而获得符合设计要求的叶片实体模型。     

汽轮机叶片断裂原因分析研究

针对锅炉软水处理存在的普遍性问题,对汽轮机垢进行了分析;对叶片进行了热力计算分析;对额定工况与堵塞工况的第5级叶片进行了强度核算;对某垃圾电站的汽轮发电机组转子叶片断裂原因进行了分析,认定了其原因在于结垢引起了局部通流面积锐减,转子叶片的受力发生了很大的变化,以导致叶片断裂。研究结果表明,通过采用加强对汽机运行参数监控的方式,可及时发现蒸汽品质的变化,提高锅炉软水处理的能力,能够实现机组长期、经济地运行。