水轮机叶片修复专用机器人及其控制系统研究

针对某电站水轮机发电机组的水轮机转轮遭空蚀和磨损损坏的修复问题,研究混流式水轮机叶片修复专用机器人,应用该机器人,改变了原来叶片现场修复时人工补焊、打磨的作业方式,节约修复时间,提高修复精度。     

基于Pro/E软件平台的混流式水轮机转轮叶片形状拟合

根据混流式水轮机叶片设计方程，基于Pro／ENGEINEER软件设计平台，对混流式水轮机叶片进行了形状拟合，得到了叶片拟合形状，完全符合叶片加工的工艺要求，也为研制水轮机修复专用机器人提供了研制条件。     

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.     

修复严重汽蚀的转轮的方法

水轮机转轮在运行一段时间后,会产生不同程度的汽蚀和磨损,它将直接影响水轮机的出力和安全运行.一般对汽蚀都采用堆焊的方法进行修复.但当汽蚀很严重,如叶片穿孔并有大面积缺口,特别是叶片出水边厚度因磨损减薄较多时,不能采用堆焊工艺,修理就比较困难了.为此,我们对转轮的修复进行了试验.     

狭窄空间修复用弧焊机械手的研制

长期以来,水轮机转轮叶片的修复工作一直是以手工焊为主,不但工人的劳动条件差,生产效率低,而且由于转轮直径大、重量重,在检修时受检修空间的限制,且没有变位机,必须在工作位置下对空间曲面的转轮叶片进行焊接。焊缝是任意形状     

一次性编程加工水轮机转轮叶片的铣胎设计

介绍了水轮机叶片的一次性编程加工,解决了每个叶片都需要单独编程的问题,实现了同一台水轮机的叶片使用同一个程序加工的目标。通过一次性编程,加工出来的叶片比每个叶片单独编程提高了加工效率、加工精度,降低了叶片的形状误差和重量偏差。     

贯流式水轮机转轮叶片参数化设计与优化

在水轮机进行优化设计的过程中,参数化表达水轮机叶片所需变量多,且优化过程计算量大,针对这些问题,提出了一种水轮机转轮叶片优化设计方法。首先,采用计算流体力学(CFD)技术,对模型水轮机进行了数值模拟;然后,采用二次曲线对水轮机叶片翼型曲线进行了参数化拟合,通过改变叶片的部分位置的比例系数,对叶片形状进行了控制;通过CFD数值模拟技术,计算了不同参数下的叶片在相同工况下的计算结果,并生成了样本空间;通过反向传播神经网络(BPNN)和遗传算法,对水轮机的效率和水力性能进行了优化计算：最后,对得到的优化结果进行了CFD数值模拟计算,并将其与原型叶片进行了对比分析。研究结果表明：优化后的贯流式水轮机效率提高了2.5%,叶片的压力分布情况得到了有效的提升;该结果证明,采用该方法优化叶片翼型曲线是有效的,并具有实际的工程应用价值。     

水轮机转轮准三维反问题设计及流场性能分析

为设计出高质量的水轮机转轮叶片,确保机组运行时各项性能指标良好,在某小型混流式水轮机的转轮设计中,采用准三维反问题设计方法获得了叶片翼型的形状及尺寸数据并建立了转轮模型,再通过对机组全流道的流场性能分析以及效率和出力计算,得到了机组内部流态顺畅且效率和出力均满足要求的研究结果。研究表明,以转轮流场状态为依据的准三维反问题叶片设计,能有效实现机组转轮与电站水文参数条件的良好匹配,进而达到提升机组效率和稳定性的目的。     

水轮机叶片铸造与热处理缺陷分析及防止

分析了水轮机组叶片铸造缺陷的产生原因和防止措施.水轮机组不锈钢叶片铸造裂纹的形成是由于铸造热应力和组织应力过大,超过了材料的抗拉强度.通过对铸态下的金相组织分析,找出了水轮机叶片铸造与热处理缺陷产生的原因,反应在生产实际中是因为生产技术操作和管理不当所致.这一结论对于水轮机组不锈钢叶片的生产及同类零件的制造具有重要的指导意义.     

轴流式水轮机叶片数控加工刀位轨迹仿真

分析了轴流式水轮机叶片的形状特点,用UG/CAD的建模技术为叶片建模.由木模图得到型值点,依据由点连线、由线成面、由面构体实体建模方法,构造叶片的几何模型,由UG/CAM生成刀位轨迹,实时观察模拟走刀过程,检查刀具与叶片之间是否产生干涉,过切等现象.     

基于单向流固耦合的潮流能水轮机叶片强度及模态分析

叶片作为潮流能水轮机叶轮的关键部件,在其工作过程中受到水流的作用力,会对其安全性与稳定性有一定的影响。文中基于Workbench,先用CFX软件对水平轴潮流能水轮机叶轮在正常流速和最大流速情况下所受流体作用力进行了稳态数值模拟;然后在Workbench内完成流体域和结构域两个物理场之间数据的传递,采用单向流固耦合的方法将流场载荷施加到叶片结构上并对其进行了强度分析,得到了叶片变形及应力的变化情况;最后对叶片进行了模态分析,得到叶片各阶模态振型、频率及最大变形量,并且对结果进行了分析。     

大型风力机叶片研究现状与发展趋势

叶片是风力机最为关键的部件之一,叶片、轮毂组成的风轮是能量捕获机构,将风能转变为机械能,与此同时,叶片又是风力机力源,主要承载部件,对整个风力机安全运行起着关键作用。在对大型风力机及其叶片产业发展现状分析基础上,从气动外形与结构设计现状、运行监测与控制技术现状、发展趋势与有待研究的问题等几个角度进行较为全面的梳理总结,从而从总体上把握现代大型风力机叶片研究现状及发展趋势。指出今后将在针对抗台风叶片、低风速叶片、仿生叶片和低噪音叶片等的个性化设计,具有外部载荷环境和自身结构状态变化感知功能的智能风力机叶片设计等方面进一步发展;已经形成的风力机叶片设计、制造及运行监控理论等还要随着大批量风力机全生命周期服役实践,进一步完善和发展。     

Estimation of power in low velocity vertical axis wind turbine

The present work involves in the construction of a vertical axis wind turbine and the determination of power. Various different types of turbine blades are considered and the optimum blade is selected. Mechanical components of the entire setup are built to obtain maximum rotation per minute. The mechanical energy is converted into the electrical energy by coupling coaxially between the shaft and the generator. This setup produces sufficient power for consumption of household purposes which is economic and easily available.     

基于遗传算法的风力机叶片优化

绍了遗传算法的基本知识并提出了风力机叶片优化设计模型,采用全局优化的方法,以叶片各截面年发电量最大为设计目标,叶片各截面处的弦长和扭角为优化变量,使用遗传算法进行了搜索寻优。以1.5 MW 风力机为例,利用 MATLAB 软件中已开发的优化程序设计并优化叶片,把用全局优化方法设计的叶片与 Glauert 方法所设计的叶片进行了比较,同时把所设计的叶片与已有叶片相比,结果表明其输出功率明显增加,从而说明了该方法的有效性。     

强流脉冲离子束辐照涡轮叶片表面的清洗加工

利用强流脉冲离子束辐照的冲击加工作用，进行涡轮叶片表面氧化物的清洗加工。强流脉冲离子束的束斑面积为10～100cm^2，离子能量为300keV，束流密度为350A／cm^2，在辐照2～20次条件下，涡轮叶片基体表面因高温氧化形成的氧化物层完全去除；辐照表面微米深度浅层的快速熔化凝固，使叶片基体表面的微观缺陷焊合。通过强流脉冲离子束辐照，获得了光滑、平整的涡轮叶片基体表面，实现了涡轮叶片表面的清洗维修。     

Enhancement of combined cycle performance using transpiration cooling of gas turbine blades with steam

Gas/steam combined cycle is synergetic combination of Brayton cycle based topping cycle and Rankine cycle based bottoming cycle, which have capability of operating independently too. Combined cycle performance depends on the constituent cycles and it can be reasonably improved by enhancing gas cycle performance using gas turbine blade cooling. Amongst different cooling techniques the transpiration cooling offers effective utilization of coolant as compared to film cooling because of better shrouding of blade surface as the coolant is discharged from entire blade surface. The present work deals with evaluation of performance enhancement of combined cycle by using steam transpiration cooling of gas turbine blades. The combined cycle performance parameters e.g. overall efficiency and specific power output etc. have been compared for air transpiration cooling and steam transpiration cooling. The results revealed that for the specified conditions the steam is superior coolant in comparison to air and the combined cycle performance can be enhanced by applying transpiration cooling in gas turbine blades with steam as coolant. With a turbine inlet temperature of 1800 K and compressor pressure ratio of 23, the combined cycle efficiency with steam transpiration cooling of gas turbine blades is higher by 1.94 percent approximately as compared to the efficiency of combined cycle with air transpiration cooling of gas turbine blades.     

A shell analysis of turbine blade vibrations

Free vibrations of turbine blades are analysed numerically by means of a general shell theory. The effect of centrifugal force is taken into account, and it is found possible to examine a wide class of blades. The continuous shell problem is discretized through a finite difference energy method, working on a simple rectangular grid mapped onto the blade surface by parameter functions. Three examples are shown, all of which are compared with previous investigations. One example considers an actual blade from the last stage of a steam turbine, while another considers a compressor blade.     

井下泥浆涡轮水力性能数值模拟及试验验证

为了提高井下泥浆涡轮的水力性能,采用NACA翼型+前弯叶片代替圆弧平板直叶片,数值模拟研究改造前后井下泥浆涡轮的内部流场和水力性能。结果表明采用NACA翼型+前弯叶片,能够有效地增加转叶压力面与吸力面的压差,降低转叶出口的能量损失,提高涡轮的输出轴功率和效率,降低涡轮进出口的压降。并通过性能试验,验证改造前后涡轮水力性能的改善效果。     

Turbine operation with nonsteady flow-analysis and experiments

The paper describes a theoretical and experimental study of the internal flows in single-stage, axial-flow pulse turbine. In the theoretical analysis, based on the method of characteristics, special attention was given to the boundary condition governing the flow from the nozzles into the rotor blades under off-design conditions. The analysis showed a momentum exchange occurring across the nozzle-rotor boundary, leading to entropy generation in the rotor passages, and corresponding energy dissipation.

Experiments conducted on a test turbine, in which turbine internal work was calculated from speed change data, showed remarkably high performance figures. A comparison of predicted performance with test measurements showed good agreement in the range of turbine speeds for which the analysis was written. It was concluded that substantial improvements in pulse turbine performance through design changes involving nozzle and rotor blades are not to be expected.     

Blade number effect for a ducted wind turbine

Ducted wind turbine with multiple blades installed was believed to have a good wind power energy conversion effect. However, little information was available on how to design a good ducted wind turbine. In this paper the effects of blade number on a ducted wind turbine performance is studied. Numerical studies using CFD method to simulate the wind turbine performance were adopted. The duct is a converging-diverging nozzle with the turbine blades located at the throat. A rated output of a 1-kW turbine is adopted as the baseline design. It was found that the blade geometry, stagger angle, and number of blades have different duct blockage effects, and do affect the turbine performance (specifically the power coefficient and torque coefficient, etc.). The fewer number of blades has higher through flow speed, while the larger number of blades provides larger torque. The best power coefficient lies in between the two extremes. The appropriate number of blades is important to match the generator performance curve for optimal overall performance and efficiency. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju Korea, October 16–19, 2007.