三头进给电解加工叶片流场特性

为合理利用流场因素对叶片电解加工的影响,提高叶片电解加工的精度和表面质量,结合自行研制的新型三头进给叶片电解加工机床,建立电解加工流场的数学模型,设计新的"双向进液"的流动形式及适应该流动形式的电解加工夹具,分析气泡率、温度、压力、流速等因素对电解加工的影响.进行叶片电解加工试验,试验表明,流场设计合理,有利于保证加工的稳定性,提高叶片加工质量,并可实现叶片叶身、缘板的全方位电解加工.     

整体涡轮大扭曲叶片电解精加工方法与试验研究

材料为高温合金的整体涡轮盘,其大扭曲叶片加工一直是制造业中的难题。提出多轴联动复合平面摆动展成电解方法加工大扭曲叶片,用一次进给电解实现叶盆、叶背面加工;分析复合平面摆动展成电解加工叶片型面成形规律,优化复合摆动展成电解加工数控编程及阴极结构设计,解决叶背出气边电解过切、根部三角区过切、出口短路等关键工艺问题;进行摆动式展成进给电解试验与分析,一次电解可达叶盆、叶背型面精加工要求。     

复合进给电解加工机床的研制

针对现有电解预加工叶片型面复杂、叶栅通道扭曲的整体叶盘时存在的加工余量分布不均、余量差过大等问题,分析了现有技术中工具电极单一直线进给的缺点,基于工具电极可直线与旋转复合进给加工方法,研制了可以实现复合进给运动的电解加工机床,并配合基于PMAC的开放式数控系统,使该机床具有高精度、高柔性、开放化等特点,同时,研究了机床最优进给路径的实现方法,从理论上证明了该方法的优点及可行性。相较于现有技术,该机床有助于提高叶栅通道的加工精度、减小加工余量差,为后续叶片型面精加工奠定了良好的加工基础。     

整体叶盘型面电解加工阴极进给方向优化及试验研究

电解加工技术是航空发动机整体叶盘零件主流加工技术之一。电解加工中阴极进给方向与阳极型面法线方向夹角的均匀性是影响加工精度的重要因素。为进一步提升整体叶盘型面电解加工精度,针对工具阴极进给方向优化设计问题开展研究。通过研究阴极进给方向与阳极型面法线方向夹角变化对电解加工极间间隙的影响,在分析传统进给方向存在的不足基础上,提出一种叶盘电解加工阴极进给方向优化方法。该方法以阴极进给方向与叶片型面法线方向夹角集合中的最大夹角值为评判指标,以评判指标值最小为判优准则。为验证优化方法的有效性,开展整体叶盘电解加工中阴极进给方向优化设计,采用黄金分割法获得了优化进给方向的最优解。与传统进给方向相比,优化后的进给方向显著提升了夹角分布的均匀性。开展传统进给方向与优化进给方向的加工比较试验以及多叶片扇段加工试验,试验结果表明采用优化进给方向可显著提高加工精度。     

基于叶栅通道可加工性分析的整体叶盘径向电解加工阴极设计及实验

为提高叶栅通道加工质量,针对径向进给的电解加工方式,分析了通道可加工性问题,通过通道模型离散化处理,得到了加工边界曲面;讨论了进给角度与加工余量均匀性的影响,确定了合理的进给方向。在此基础上对阴极侧面轮廓和端面型面进行了设计,并制备了加工所需的工具阴极,利用自行研制的整体叶盘电解加工平台开展了工艺实验。结果表明:加工出的通道试件轮毂成形精度高,叶根部位加工质量好,叶盆、叶背余量分布均匀一致,能够满足后续叶片精加工要求。     

镍基高温合金整体叶盘叶栅通道电解加工的成形精度控制

针对整体叶盘叶栅通道电解加工中存在的成形精度较低、余量分布不足的问题,采用叶栅通道径向电解加工方法,建立了径向进给方式中加工间隙的数学模型,得到了通道成形过程中侧面间隙的影响规律。在此基础上,分析了电极侧面裸露端、电解液特性、脉冲电流参数以及进给速度等对通道成形的影响,并给出了优化结果。同时开展了叶栅通道径向电解加工实验研究,结果显示:采用优化后的各项参数,在高温镍基合金GH4169叶盘上稳定地加工出了具有较高成形精度的叶栅通道,其叶盆、叶背面的最小精加工余量从1.82 mm和1.56 mm分别提高至2.43 mm和2.41 mm。为后续叶片精加工提供了良好的加工基础。     

大扭曲度整体涡轮叶片展成电解加工成形规律及试验研究

根据大扭曲度整体涡轮结构特点与加工难点，提出用展成电解方式实现其叶片加工；分析、研究大扭曲度整体涡轮展成电解加工叶片型面成形规律；根据其成形特点，进行多轴联动数控编程的优化；合理设计阴极及流场，对叶背二次腐蚀、出口短路及叶背余量去除等关键工艺问题进行分析讨论并提出有效解决措施；进行整体涡轮叶片展成电解加工试验，可稳定达到型面精度加工要求，为大扭曲度整体涡轮展成电解加工的应用创造了条件。     

复合平面摆动展成电解加工整体构件异形面的成形分析及应用

各类新型航空发动机中大量采用整体结构件,其异形面加工一直是机械制造中的难点。提出整体构件异形面的复合平面摆动展成电解加工方法,用一次进给“电解”达到型面加工要求。分析复合平面摆动展成电解间隙动态过渡过程,进行成形规律分析;以整体涡轮大扭曲叶片型面为研究对象,优化复合摆动展成进给加工轨迹,设计有补液流场的薄片底板与阴极体的组合式阴极,进行复合摆动展成进给电解加工试验,一次进给电解同时去除叶片通道两面余量,达到精加工效果;验证此方法加工变断面整体构件在生产率、精度、成本等方面的技术优势,为复合平面摆动展成电解工艺的拓展应用建立基础条件。     

长窄型薄壁叶片的套料电解加工

为实现长窄型薄壁叶片的套料电解加工,设计了电解液沿叶片轮廓四周进液的流动方式,开展了导流式出液和开放式出液的仿真对比分析,结果表明,导流式出液可以明显改善加工区域内流场的均匀性。开展了薄壁叶片套料电解加工试验研究,在进给速度1.4 mm/min下实现了薄壁叶片的套型加工,轮毂表面粗糙度从0.532 μm 降低至0.307 μm,叶片型面粗糙度从0.816 μm 降低至0.583 μm。     

复合进给电解加工机床进给机构的研制

基于对复合进给电解加工机床进给机构结构及工况特点的研究与分析,以直线运动系统和回转运动系统为主要研究对象,结合其运动特点和精度要求,提出了其设计难点,给出了其核心部件的选用要求、加工和装配工艺以及整机的精度控制措施。经实测验证,该机床进给机构各项技术指标均满足设计要求,为复合进给电解加工方法的实现提供了可靠的实验装置,同时,对于类似低速高精度进给机构的设计具有重要的参考意义。     

新型并串联机床加工叶片程序的后置处理与仿真

用并联机床加工汽轮机叶片时 ,往往受其工作空间的限制而不能在最佳的切削姿态下进行加工。因此我们在并联机床六轴联动的基础上 ,再串联一个数控转台 ,实现七轴联动 ,即可在一次装夹过程中 ,以最佳的切削姿态完成叶片汽道型面、叶顶、叶根圆角、进、出汽边圆角的加工。本文给出了七轴联动并串联机床加工叶片时的坐标变换公式及数控加工程序的计算机仿真验证方法     

Integrated aero-structural optimization design of pre-bend wind turbine blades

In the optimization design of a pre-bend wind turbine blade, there is a coupling relationship between blade aerodynamic shape and structural layup. The evaluation index of a wind turbine blade not only shows on conventional ones, such as Annual energy production (AEP), cost, and quality, but also includes the size of the loads on the hub or tower. Hence, the design of pre-bend wind turbine blades is a true multi-objective engineering task. To make the integrative optimization design of the pre-bend blade, new methods for the blade’s pre-bend profile design and structural analysis for the blade sections were presented, under dangerous working conditions, and considering the fundamental control characteristics of the wind turbine, an integrated aerodynamic-structural design technique for pre-bend blades was developed based on the Multi-objective particle swarm optimization algorithm (MOPSO). By using the optimization method, a three-dimensional Pareto-optimal set, which can satisfy different matching requirements from overall design of a wind turbine, was obtained. The most suitable solution was chosen from the Pareto-optimal set and compared with the original 1.5 MW blade. The results show that the optimized blade have better performance in every aspect, which verifies the feasibility of this new method for the design of pre-bend wind turbine blades.

     

Design of the cross-structural cathodes in electrochemical machining of aero-engine blades

Blades are crucial parts of aero-engines. Their manufacturing is difficult because of their thinness, complex profile and stringent requirements. Electrochemical machining (ECM) is an important approach for manufacturing blades, but it is difficult to machine the leading and trailing edges. This article adopts cross-structural cathodes in ECM to solve the open electric field space problem. The key difficulty in the design of cross-structural cathodes is the position of the crossed-point. The height and the offset of the crossed-point are optimized using the ANSYS software. The simulation results show that the position of the crossed-point obviously affects the machining accuracy, along the leading and trailing edges of the blade. A pair of cross-structural cathodes with one uniform section is designed, and a series of corresponding ECM experiments are carried out. The experiments demonstrate that the ECM process is stable, the profiles are sleek and the machining dimensional error is reduced to 0.08 mm at the leading and trailing edges of the blade when using the new cathode structure.     

基于模糊综合评判与故障树法的燃气轮机故障诊断

燃气轮机作为一种多功能供能机械,被广泛地应用于我国海上平台的生产作业,直接为平台的各个系统输送电能,其正常工作对整个平台的正常生产起到关键的保障作用;但是,近年来我国沿海钻井平台使用的不同型号发电机组时有发生叶片断裂的事故,造成严重的生产损失,所以研究故障叶片的诊断具有重要意义。本文运用一种将模糊综合评判与故障树分析法有机结合的诊断方案,克服了传统故障树诊断技术中难以解决的随机不确定性和复杂模糊性问题,并且以某作业区海上平台燃气轮机故障叶片为例,阐述了运用该方法对叶片故障原因进行的精确诊断。     

六轴联动叶片型面砂带磨削方法及加工仿真研究

依据砂带接触轮与叶片型面的最佳接触条件,提出了叶片型面六轴联动砂带磨削加工方法,并进行了叶片砂带磨削的刀位点计算;采用VERICUT构建了虚拟数字机床并进行了仿真加工实验,验证了叶片型面砂带磨削加工刀位点以及轨迹计算的正确性.     

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.     

透平叶片五轴数控加工工艺技术研究

针对透平叶片,提出了一种加工工艺过程和编程方法。根据叶片的几何特性,安排合适的加工策略,对生成的刀具轨迹进行仿真,并在五轴加工中心上进行试切,最后在三坐标上检测,经验证叶片的加工质量达到设计要求。     

变壁厚涡轮冷却叶片参数化造型设计

提出了一种基于函数解析的变壁厚涡轮冷却叶片参数化设计方法。根据叶片外型线上定义的若干参数点,采用三次样条插值方法得到叶片壁面厚度分布函数,再通过计算得到冷却通道型线上离散数据点,在CAD平台下建立了变壁厚涡轮冷却叶片参数化模型。为实现涡轮冷却叶片的自动设计优化和多学科设计优化,获得更佳的叶片设计方案奠定了基础。     

AERODYNAMIC OPTIMIZATION FOR TURBINE BLADE BASED ON HIERARCHICAL FAIR COMPETITION GENETIC ALGORITHMS WITH DYNAMIC NICHE

A global optimization approach to turbine blade design based on hierarchical fair competition genetic algorithms with dynamic niche (HFCDN-GAs) coupled with Reynolds-averaged Navier-Stokes (RANS) equation is presented. In order to meet the search theory of GAs and the aerodynamic performances of turbine, Bezier curve is adopted to parameterize the turbine blade profile, and a fitness function pertaining to optimization is designed. The design variables are the control points' ordinates of characteristic polygon of Bezier curve representing the turbine blade profile. The object function is the maximum lift-drag ratio of the turbine blade. The constraint conditions take into account the leading and trailing edge metal angle, and the strength and aerodynamic performances of turbine blade. And the treatment method of the constraint conditions is the flexible penalty function. The convergence history of test function indicates that HFCDN-GAs can locate the global optimum within a few search steps and have high robustness. The lift-drag ratio of the optimized blade is 8.3% higher than that of the original one. The results show that the proposed global optimization approach is effective for turbine blade.     

基于UG的水轮机叶片的逆向反求

借助三坐标测量机测量叶片原始点数据并在三维CAD软件UGS NX中用进行三维造型的逆向反求工程方法.叶片建模的点数据来自实物叶片的测量资料,包括样板曲线和叶片表面上不规则的测量点云.逆向反求过程为数据采集、数据处理转换、数据导入、创建叶片轮廓曲线、用三维数据创建叶片轴面型线、创建叶片网格曲线、创建叶片外表面曲面、创建叶...