汽轮机叶片的建模及插补算法研究

为提高汽轮机的工作效率,汽轮机叶片的表面通常是设计成扭曲的变截面曲面,叶片形状十分复杂,因此,汽轮机叶片的精确几何造型对保证叶片加工质量十分重要。进行汽轮机叶片数学建模和数控插补算法研究,根据图纸数据对汽轮机叶片进行基于NURBS曲线和曲面的反求计算,建立了汽轮机叶片的精确数学模型。针对叶片高速高精度数控加工的要求,以叶片数学模型为基础,建立叶片截面的NURBS曲线组,利用MATLAB编程仿真,验证了采用不同插补算法进行叶片数控加工的适应性。     

汽轮机700mm叶片原始数据处理

通过分析汽轮机700mm叶片的成型规律及计算公式,针对该叶片的特点,提出采用分区等弧长法计算各截面节点坐标;并按等行距法对叶片型面的加工行距和刀具尺寸进行估算,为应用均匀双三次B样条曲面反算法拟合叶片型面及实现其数控砂带磨削加工提供准确的数据。     

汽轮机叶片型面的三维曲面构造

应用双三次均匀Ｂ样条曲面，建立了对给定型值点的汽轮机片进行曲面构造和等距曲面计算的数学模型，为叶片型面的数控加工提供了依据。     

用于汽轮机末级长叶片优化的前处理方法

对由气动设计所得到的初始叶型,通过曲面蒙皮技术得到参数化曲面片,并将物理域边界统一成与叶片相同的参数曲面形式,建立求交点交线算法.通过提出几何拓扑关系和疏密系数,自动生成三维贴体网格.本方法可用于叶片较大弯扭的末级长叶片优化设计.     

基于LabVIEW的汽轮机叶片动态特性测量系统开发

叶片是汽轮机的重要工作部件,为了研究其在不同激振力下的振动特性,针对实验室新搭建的汽轮机叶片动态特性试验台,基于LabVIEW开发了用于测量和分析汽轮机叶片振动测量系统.该测量系统具有叶片振动信号采集、信号处理、信号分析、数据保存和数据回放功能.在本文中,将介绍实验台组成、测量系统硬件选型、系统开发流程和各功能模块的编程.最后,采用该系统做了叶片静频和动频的测量实验,结合理论分析和实验结果表明,该测量系统是可靠的.     

汽轮机叶片虚拟制造仿真研究

文章通过VERICUT平台,定制开发汽轮机叶片虚拟仿真控制系统,实现汽轮机叶片虚拟制造仿真.该仿真控制系统可提高汽轮机叶片数控加工程序的安全性、产品质量、制造系统的工作效率和数字化车间基础数据的准确性.     

基于ICEM CFD对汽轮机末级三维叶片流场网格划分方法的优化

网格的划分是对工程问题进行数值模拟的重要环节,网格质量的高低直接影响计算结果的精度.在对汽轮机叶片周围流场的数值模拟过程中,较高质量的网格是基础要求,但由于汽轮机末级叶片结构非常复杂,这就加大了其网格划分过程中的难度.为了进一步提高ICEM CFD对汽轮机叶片周围流场网格划分的质量,并针对避免产生“负体积”的问题.提出了一种可以得到高质量网格的方法,并阐述了在实际操作中应该注意的事项.     

煤场存煤量测量中煤堆三维立体图生成方法研究

对大型露天煤场存煤量测量中激光扫描采集到的三维不规则数据场的显示方法进行了研究，提出了一种基于平面域三角剖分的显示算法。首先对三维深度数据在矩形平面域上投影，并对平面域内的采样点按Ｄｅｌａｕｎａｙ优化准则进行三角剖分，然后把网格节点变换到三维曲面上，从而实现了煤堆三维立体图的显示。它可直观地给出煤场存煤体积的测量结果，并可提高体积计算的精度。该算法已成功用于露天煤场存煤量测量系统。实验结果表明了该     

粗加工曲轴相位专用测量工具的设计与应用

简要介绍ZD30四缸曲轴粗加工相位的测量方法及其检具的设计.并使用曲轴综合测量机测量曲轴,其测量数据和检具测量数据进行对比分析,为检具准确性的确认提供了依据.检具操作简单,满足了现场快速测量的需要,测量数据直接可指导加工机床的精度调整.     

汽轮机叶片三维有限元模型的建立及静态与动态应力分析

为了获得汽轮机叶片更为真实详细的应力状态，建立三维实体模型并采用合适的有限元模型进行分析是非常必要的。本文给出了完成叶片三维应力分析所必须的三个步骤并提供了相应的方法：叶片三维有限元计算网格的自动生成，合适的静态与动态应力有限元分析模型的建立，有限元分析结果的后处理方法。文中最后还使用本文提供的方法分析了一个汽轮机末级长叶片和五片成组叶片的静态与动态应力，计算结果与实验数据进行了对比，表明了计算模型的精确度以及应力分析系统的工程实用性。     

带小冠静叶片的数控加工

针对东方汽轮机厂600MW,1000 MW汽轮机低压带小冠静叶,采用集成化的先进工艺、工装和高度智能的数控加工手段来提高加工效率,减少加工与管理环节,提高叶片的加工质量从而保证机组的设计效率。     

Natural Convection around Horizontal Tubes with Smooth,Rough, and Machined Surfaces

This study concerns natural convection around horizontal tubes with smooth, rough, and machined surfaces. The study is motivated by the need for understanding the machining effect or the use of a rough surface layer on the natural convection process. An experimental system is constructed that includes a thick wall metal tube equipped with thermocouples for measuring the surface temperature. A heating element is inserted inside the tube and is coupled with a power supply that can be adjusted to achieve surface temperatures of 60–160°C. The tube surface is machined at various depths of 1–3 mm. Also, four grades of sandpaper are used to cover the tube surface. An analysis of measured data is based on variations in the Nusselt number as a function of the Rayleigh number and surface condition. Results show that the measured data for the smooth tube are consistent with literature results. Although surface machining increases the heat transfer area, it lowers the heat transfer rate because of the low thermal conductivity of air, which replaces the removed metal in the machined grooves. Similarly, covering the tube surface with sandpaper reduces the rate of heat transfer from the tube surface because of contact resistance and the thermal resistance of the sandpaper. Data analysis that takes into consideration the above resistances, where the contact and sandpaper thermal resistances are eliminated, show enhancement of up to 30%. This implies that the direct roughening of a metal surface would enhance the heat transfer rate by 30%.     

Experimental Study of Heat Transfer in Gas Turbine Blades Using a Transient Inverse Technique

To enhance specific power output and thermal efficiency of gas turbine engines, industry searches for ways to increase the turbine inlet temperatures. Therefore, temperatures of turbine blades increase as well and necessitate active cooling of these components. Experimental design work on such internal cooling schemes is carried out to find acceptable compromises between heat transfer and pressure losses. It is often carried out by using transient thermochromic liquid crystal techniques in combination with Plexiglas models. However, for real turbine blades this experimental technique is inappropriate due to the lack of optical access. Therefore, to study actual turbine blades there is need for development of noninvasive, nondestructive methodologies. This article describes a measurement technique that allows determination of internal heat transfer coefficients of real turbine blades experimentally. Thus, a test rig with a rapidly responding heater was designed to fulfill the requirement of a sudden increase in the air temperature within the cooling passages. The outer surface temperatures were measured using infrared thermography. To estimate the spatial distribution of internal heat transfer coefficients from transient surface temperatures the inverse heat transfer problem was solved. As optimization algorithm the Levenberg–Marquardt method was chosen. Outer surface temperature data was measured for a rectangular reference model with rib turbulators and compared with simultaneously acquired data using the thermochromic liquid crystal technique. It is concluded that the new experimental measurement technique could be used to quantitatively determine internal heat transfer coefficients.     

Application of a control algorithm for wind speed prediction and active power generation

The main objective of the work described in this paper is to offer a new method of prediction of wind speeds, whilst aware that the method develops predictions in time-scales that can vary from a few minutes to an hour. This is needed because wind energy generation is increasing its participation in energy distribution and has to compete with other energy sources that are not so variable in terms of generated active power. It is important to consider that active power demand can vary quite rapidly and different sources of electricity generation must be available. In the case of wind energy, wind speed predictions are an important tool to help producers make the best decisions when selling the energy produced. These decisions are crucial in the electricity market, because of the economic benefits for producers and consequently their profitability, depends on them. The algorithm presented in this paper is based on an artificial neural network and two types of wind data have been used to test the algorithm. In the first, data was collected from a not very windy area; in the second data was collected from a real wind farm located in Navarre (North of Spain), and the values vary from very low to high speeds. Although the algorithm was not tested with typical wind speed values measured on offshore wind farm applications, it can be concluded from the first set of results presented in this paper that the algorithm is valid for estimating average speed values. Finally, a generic algorithm for the active power generation of a wind farm is presented.     

基于VERICUT的汽轮机大叶片数控加工仿真的应用

利用数控加工仿真软件VERICUT实现了汽轮机大叶片四坐标数控加工仿真.该仿真系统针对四坐标加工中心建立了相应的刀具、机床、回转工作台和夹具模块以及配置了机床控制系统,详细介绍了各个子系统的体系结构、功能以及实现的关键技术.以汽轮机大叶片为例,利用仿真模块对四坐标加工进行动态仿真,实现了汽轮机大叶片的四坐标虚拟加工中的"干涉、过切及碰撞"检查.     

连杆小头球面加工新方法

对柴油机连杆小头球面加工的几种方法进行了比较分析。从加工效率、加工质量以及企业的实际情况出发,批量化生产选用THK6111数控卧式镗铣床和专用夹具的加工方案,最终实现连杆小头球面的粗精加工,尺寸及表面粗糙度均达到要求。该方案有效利用了工厂现有设备,节约了生产成本。     

一种海洋能及风能联合发电装置

文章提出了一种利用海洋温差能和风能联合发电的方法及装置。利用海洋表层的热海水加热低沸点工质,使之蒸发．送入汽轮机推动汽轮发电机组做功发电,汽轮机排出的工质乏气用海洋深层的冷海水冷凝为液态,再用热海水加热,送入汽轮机,使之蒸发,推动汽轮机发电机组做功发电,如此循环,持续发电;并且利用洋面风力发电,并用该电力驱动热泵装置．由热泵装置的媒质将工质的温度进一步提高．增大工质体积膨胀率;由热泵装置的媒质将冷海水的温度进一步降低．再用该低温海水去冷凝工质乏气,增强对工质乏汽的冷凝效果。该装置既需要用到小型透平,又需要用到风力发电装置．十分适合公司发展。     

1000MW汽轮机低压转子轮槽成形铣刀加工性能研究

采用成形铣刀加工1000MW汽轮机低压转子末级轮槽,通过对26NiCrMoV145转子钢材料切屑的形成情况、刀具磨损形貌以及加工后材料表面残余应力大小的分析,研究成型铣刀的加工性能。结果表明:材料的切屑以带状切屑为主;粗刀以刀刃处边界磨损居多,而半精刀以前刀面损伤更为突出;加工表面残余应力多为残余压应力。     

EMD在LabVIEW中的实现及其在水轮机主轴振动信号分析中的应用

针对LabVIEW中缺少经验模态分解(EMD)算法模块的问题,对LabVIEW进行了二次开发,建立了基于LabVIEW的EMD模块,为振动故障信号分析提供了有效的工具,进而以水轮机故障信号的振动特征和故障产生机理为依据,将此算法运用于水轮机主轴振动信号分析,以河北省西达水电站水轮机主轴振动数据为基本资料,对分解得到的高频本征模函数(IMF)分量做包络谱分析,提取故障信息,并与轴心轨迹分析方法相结合加以验证。结果表明,该方法能够有效判别出水轮机主轴故障类型,可应用于水轮机主轴振动信号分析。