汽轮机高压喷嘴组加工

分析了汽轮机高压喷嘴组在加工过程中存在的主要难点,介绍了车加工和铣镗加工汽轮机高压喷嘴组主要部件的具体加工工艺.希望同行业有关人员加以借鉴,对汽轮机高压喷嘴组的制造难点和设计工艺进行研究,探讨出行之有效的方案,满足整个生产工艺的要求.     

双缸汽轮机喷嘴组连接器的试压工装设计及工艺简介

简要介绍了双缸汽轮机喷嘴组连接器的试压技术要求，针对试压难点，设计了一种既简便又实用的试压工装。     

Wear characteristics of commercial gas turbine components

Wear is one of the common degradations in a commercial gas turbine. A stainless steel grade 304 (SS 304) fuel nozzle and its collar made of nickel-based superalloy (Hastelloy X) are two vital components that normally suffer from rapid wear. During an installation, the fuel nozzle is slotted into the collar of the combustion liner. In operation, these two surfaces are subjected to high pressure from the fuel combustion, hence continuously rubbing against each other causes vibrations. During the start–stop operation, these surfaces had undergone a large relative motion. The vibration is the main cause of the wear occurrence on the surfaces. Physical properties of the worn surfaces were obtained through visual observations: wear measurement, hardness and microstructure examination. Through visual observations, fretting wear was mainly suspected as the dominant wear mode, particularly after 8,000 of running hours at high temperature and vibration. In short, this paper discusses the preliminary findings of wear on the fuel nozzle and its collar. It also discusses the changes in the mechanical properties before and after the operation. Solutions for mitigating the problem were discussed.     

基于多目标优化的柴油机VNT–vEGR系统开发研究

为了在兼顾柴油机经济性和颗粒物排放的前提下,进一步降低氮氧化物(Nitrogen oxides,NO_x)排放以实现良好的柴油机综合性能,设计带文丘里管废气再循环系统的可变涡轮增压系统(Variable nozzle turbo+Venturi-exhaust gas recirculation,VNT+vEGR)。针对排气旁通阀涡轮增压(Wastegate,WG)柴油机原机,进行文丘里管废气再循环系统(Venturi-exhaust gas recirculation,v EGR)的设计和与可变涡轮增压器(Variable nozzle turbo,VNT)的匹配研究,并进行经济性、氮氧化物和颗粒物排放仿真计算研究。应用试验设计方法技术(Design of experiment,DoE)对VNT-vEGR系统进行多目标优化研究。研究结果表明,相比于配备排气旁通阀涡轮增压器的柴油机原机,对VNT-v EGR系统柴油机应用Do E进行多目标优化匹配后,欧洲稳态测试循环(European steady-state cycle,ESC)工况加权油耗值基本保持不变,氮氧化物加权排放量下降约49.5%,能够实现良好的综合性能。     

分体滑动导叶可调涡轮激波与载荷波动机制

针对某柴油机用可调涡轮在低速工况下的低效强激波特征,提出并设计了一种分体滑动导叶,并在10%、40%和100% 3个典型开度下进行了定常/非定常数值计算。结果表明：分体滑动导叶在小开度下可实现对间隙泄漏流动的有效抑制,大幅度提高涡轮效率;在10%开度下,分体滑动导叶提高了涡轮10%的峰值效率,同时涡轮效率在40%和全开工况下也有不同程度的提高。此外,通过合理设计转静间距,分体滑动导叶尾缘激波被大幅度削弱。导叶间隙泄漏流和尾缘激波的抑制可有效弱化转子定子干涉强度,降低下游转子叶片表面载荷波动幅值,提高转子叶片的可靠性。     

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.     

数字孪生驱动的航空发动机涡轮盘剩余寿命预测

为解决航空发动机涡轮盘剩余寿命在线预测难题,提出一种数字孪生驱动的涡轮盘剩余寿命预测方法。在建立数字孪生模型的过程中,首先,分析涡轮盘疲劳裂纹损伤机理,构建性能退化指标,建立涡轮盘性能退化过程的共性表征模型;其次,分析多种不确定性因素,采用状态空间模型建立涡轮盘性能退化过程的个性表征模型;然后,通过动态贝叶斯网络描述状态空间模型随时间的演化规律,建立涡轮盘性能退化过程的动态演化模型;最后,采用粒子滤波算法实现涡轮盘退化状态追踪和剩余寿命预测,从而完成涡轮盘性能退化数字孪生模型的建立。融合涡轮盘实时传感数据,通过贝叶斯推理实现对该数字孪生模型的动态更新。通过某型涡轮盘试验数据对该方法进行验证,结果表明该数字孪生模型能够较好地解决涡轮盘剩余寿命在线预测问题。     

对转涡轮低压转子叶片的流固耦合数值分析

采用对转涡轮设计能提高航空涡轮发动机性能,其中无导叶方案是发展趋势之一。在无导叶对转涡轮中,低压转子叶片受到较大的高压转子出口气流激励。基于ANSYS/CFX软件,采用流固耦合数值分析方法对低压涡轮转子叶片进行了分析,得到了高压涡轮转子叶片尾流作用下的低压涡轮转子叶片振动的应力和变形变化规律。叶片温度对振动应力和位移的平均值、幅值和周期的影响较大,叶片材料密度对振动周期产生明显的影响,高低压转叶轴向间距的选择应兼顾涡轮效率等因素。     

含水量对汽轮机油润滑性能的影响

舰用防锈汽轮机油为抗氧防锈型汽轮机油,采用标准试验方法很难就水分对其润滑性能的影响进行有效评价。利用高频往复试验机和Timken试验机,用改进的试验方法考察了含水量对舰用防锈汽轮机油润滑性能的影响。结果表明：改进的试验方法试验结果区分性较好,可用于油水乳化液润滑机制的研究;水分降低了舰用防锈汽轮机油的润滑性能,当汽轮机油含水量超过0.5%时,汽轮机油的极压抗磨性能显著下降。     

基于PIC30F4012的电控系统的设计与仿真

介绍了一种可变喷嘴涡轮增压器的电控系统。系统以PIC30F4012微控制器为核心,简述了系统的硬件、软件设计,并采用数字PID控制。结合系统的动态性能,在自行构建的软硬件系统上进行了仿真。实践表明,该电控系统动态性能良好。     

水力喷射径向水平井射流钻头优选试验研究

射流钻头的破岩性能对井眼深度和大小有重要影响。本文对径向水平井常用的2种射流钻头——多孔喷嘴和混合射流喷嘴采用室内试验的方法对它们的破岩规律和破岩性能进行了分析和对比。结果表明,冲击时间、喷嘴压降、喷距和围压对2种喷嘴破碎效果的规律基本相同,混合射流喷嘴的最优喷距不明显,多孔喷嘴的最优喷距为5～6倍喷嘴当量直径,多孔喷嘴的破岩性能要优于混合射流喷嘴,同时混合射流喷嘴在破碎孔径大小方面优于多孔喷嘴。本文可以为水力喷射径向水平井射流钻头的选择提供试验依据。     

电火花修复涡轮导向叶片试验研究

研究了电火花修复K418涡轮导向叶片,为涡轮导向叶片的修复提供了理论依据.通过观察试样金相组织及测量显微硬度,并对所得试验数据进行分析,得出结论:修复后试样的金相组织较修复前均匀,晶粒明显细化;修复后试样硬度值一般提高30～50 HV,可以推断试样的耐磨性将会得到改善;最优工艺参数为电压65V,功率B2,频率C1,最大影响因素为电压;修复中还存在气孔、裂纹等缺陷,可以通过进一步试验,比如对试样进行预热、缓冷、改变材料成分等加以避免.     

一种可调叶片喷嘴结构设计与性能分析

通过跨音速喷嘴内流动机理的分析,针对某中低温地热能发电系统中透平膨胀机的运行条件,设计了与之匹配的叶片喷嘴,提出了一种新颖的叶片喷嘴调节结构形式.采用数值计算方法,研究叶片不同头部型线和不同喉部位置对喷嘴内流动及其性能的影响以适应调节机构的要求.研究结果表明:在满足工程设计要求的前提下,头部型线及喉部位置对叶片喷嘴气动性能的影响都比较小,改型后的直线圆弧型跨音速可调叶片喷嘴具有良好的变工况性能.     

低雷诺数涡轮性能计算研究

以某单级涡轮和某两级涡轮为研究对象,基于发展的子午面流线曲率法计算程序,采用四种含雷诺数效应的损失模型,对涡轮气动热力性能进行了数值模拟计算分析,对比分析了各种损失模型在基本假设、损失机理、损失预测、涡轮性能计算方面的差异.论文特别针对低雷诺数工作条件下航空燃气涡轮的性能进行了数值计算,分析研究了雷诺数变化情况下,涡轮性能变化的规律,比较了不同涡轮损失模型对低雷诺数涡轮性能计算的结果.分析结果表明,由于在基本原理和基本假设等方面的差异,不同损失模型的适用条件不同,预测结果差异也较大,在涡轮设计中应特别予以注意.     

基于FLUENT的后混合磨料水射流喷嘴内流场的数值模拟

以后混合磨料水射流喷嘴为研究对象,基于多相流动的欧拉模型,应用FLUENT流体分析软件对几种典型后混合磨料喷嘴的内流场进行数值模拟和仿真,得到压力分布、速度分布、湍流能量分布.结果表明:喷嘴内由于涡旋的形成损耗了部分能量,使得射流出口速度和动能明显降低;存在一个最优圆柱长度使得磨料出口速度达到最大值,其长度为喷嘴出口直径的23～37倍时,磨料得到最高的出口速度;喷嘴内流体紊动能的分布主要集中在喷嘴近壁区和几何形状变化较大的区域.     

Effect of wave conditions on the performance and internal flow of a direct drive turbine

The purpose of the present study is to investigate the effect of wave conditions on the performance and internal flow of a newly developed direct drive turbine (DDT) model for wave energy conversion experimentally. All the experiments using the test turbine models are conducted in a 2-D wave channel. Monochromatic waves of various conditions of wave height and wave period are applied to the turbine performance test. The influences of turbine configuration on turbine performance are also investigated. Test results show that rotational speed, differential pressure, incident flow rate, maximum output power, and best efficiency of the turbine model vary considerably depending on the wave conditions. Installation of a front guide nozzle and a rear water reservoir to the test turbine improves the turbine performance. Large passage vortex occurs both at the front and rear turbine nozzles in turn through a reciprocating flow in the turbine passage. This paper was recommended for publication in revised form by Associate Editor Jun Sang Park Young-Do Choi received his B.E. and M.E. degrees in Mechanical Engineering from Korea Maritime University, Korea in 1996 and 1998, respectively. He received his Ph.D. in Engineering from the Yokohama National University, Japan in 2003. Dr. Choi is currently a research professor at the School of Mechatronics, Chanwon National University in Changwon, Korea. His research interests include ocean energy, wind power, small hydro power, fluid machinery, PIV and CFD. Chang-Goo Kim received his B.E. and M.E. degrees in Mechanical Engineering from Korea Maritime University, Korea in 2007 and 2009, respectively. Mr. Kim is currently a doctorate student in the Department of Mechanical Engineering, Graduate School, Korea Maritime University. His research interest includes ocean energy. Young-Ho Lee received his B.E. and M.E. degrees from Korea Maritime University, Korea. He received his Ph.D. in Engineering from the University of Tokyo, Japan. Dr. Lee is currently a Professor at the Division of Mechanical and Information Engineering, Korea Maritime University. His research interests include ocean energy, wind energy, small hydro power, fluid machinery, PIV, and CFD.     

喷嘴雾化流场数值仿真及结构改进研究

针对空气喷嘴形状对雾化性能影响的问题,对不同扇面结构参数下的空气喷嘴的雾化性能进行了研究,对空气喷嘴结构参数与雾化流场之间的规律进行了归纳,提出了一种空气喷嘴的结构模型,基于雷诺N-S方程与标准K-ε湍流模型以及标准壁面函数法,采用CFD方法对不同扇面孔数量及不同扇面锥角下的空气喷嘴的雾化性能进行了数值仿真,分析了空气喷嘴不同扇面参数的改变对雾化性能的影响,并通过搭建喷枪台架实验,对优选的结构模型进行了实验验证。研究结果表明,仿真结果与实验数据基本符合要求,改进后的空气喷嘴雾化性能得到了改善,为今后空气喷嘴结构的优化设计提供了一定的参考。     

收缩-扩散型喷嘴内高速泡液流稳态解的分岔

空化水射流技术的关键是空化喷嘴 ,实验证明空化喷嘴出口形状对喷嘴的空化效果影响很大。对在具有收缩 扩散形状的喷嘴内高速泡液流稳态解的分析表明 :泡液流中很小的空隙率亦强烈地影响着其流动特性。当空隙率为临界值αc=1.895 993× 10 -4时 ,泡液流稳态解出现分岔现象。收缩 扩散型出口形状更利于喷嘴产生空化     

Study of the nozzle flow in a cross-flow turbine

An investigation of the flow inside the nozzle of a Cross-Flow turbine, which is a hydraulic turbine where the rectangular water jet issuing from the nozzle crosses the rotor blades twice, is presented here. Part of the investigation consisted in the experimental measurement of the static pressure distribution on the inside walls of two different nozzle configurations, both with the nozzle mounted alone and in the presence of a rotor. The tests performed in the presence of a rotor included the measurement of efficiency and covered a wide range of working conditions around the best efficiency point. The analysis of the results obtained in this way give us an indication of the influence of the turbine non-dimensional volume flow rate on the flow inside the nozzle and the way it affects the reaction degree of the machine and its efficiency level. Although most of the tests were carried out with a 25-blade rotor, one of the analysed nozzle configurations (that with an inside vane) was also tested with a 10-blade rotor, permitting the assessment of the effect the number of blades has on the flow in the nozzle.The flow inside the nozzle with no inside vane was numerically analysed using a method based on a Schwarz-Christoffel conformal transformation of variables. The numerical results show a fair agreement with the experimental data collected when the rotor was not present. A qualitative discussion of some of the losses occurring in the nozzle is advanced based on the computer results, and its conclusions are used for explaining the poor performance of the nozzle with no inside vane.     

基于CFD的圆柱形喷嘴设计

喷嘴是流体最后通道,起到最后加减速,控制雾化度、出口速度、喷射射程的关键部件.用三维数值分析软件对影响喷嘴喷射性能的各个参数进行定量的模拟分析,通过计算得出喷嘴出口速度,最后比较各个不同结构的喷嘴出口流速来确定最佳的喷嘴结构形式.得出喷嘴在收缩角度为12°～14°,喷嘴出口端与入口端直径比在0.5～0.6,出口整流段长...