基于三维实体模型的自带围带叶片扭转恢复角的计算

采用三维实体模型,对自带围带的汽轮机扭曲长叶片的扭转恢复角进行了计算分析。借助通用有限元软件ALGOR,建立了叶片围带间接触约束的分析模型,以探讨阻尼围带对叶片扭转恢复特性的影响。并对1 029mm叶片进行了分析计算,结果表明:自由叶片的扭转恢复角与转速成平方的关系变化;在不同的初始间隙范围,叶顶的扭转恢复角对间隙δ变化的敏感程度不同,在间隙0.50mm~1.00mm时,较为敏感,在设计时,应避开敏感区间;随着θ的增加,叶顶的扭转恢复角增加,基本呈线性变化关系。本文的研究为整圈连接阻尼叶片的设计及优化提供了指导。     

有限元技术在空冷汽轮机长叶片设计中的应用

首先采用有限元技术对某空冷汽轮机低压末级长叶片的整圈振动特性进行计算,随后时由整圈自锁长叶片围带和凸台不同接触间隙造成整圈振动特性的变化进行了数值分析,最后对空冷低压长叶片各个部分的强度进行了分析.有限元计算结果与动频试验的结果偏差很小,强度计算结果也满足设计规范的要求.这些先进计算技术的应用,大大缩短了长叶片的研发周期,保证了空冷低压长叶片的安全运行.     

叶片频率计算方法研究

采用有限元法模拟计算汽轮机中短叶片的整圈频率时,可能遇到计算模型无法形成整圈的情况。尝试采用叶片围带穿拉筋和设置围带接触面过盈的方法使计算模型形成整圈结构,并对已有的某级叶片测频结果进行对比分析,发现设置围带接触面过盈的方法能较好地反应叶片的整圈频率变化趋势。     

整圈阻尼叶片的有限元分析方法研究——稳态应力计算

整圈阻尼叶片是汽轮机动叶片中较为先进的一种长叶片结构形式,其结构强度较高,但是对其进行精细化设计和分析具有一定难度。目前在应用FEA软件对汽轮机整圈自锁阻尼叶片进行结构分析时,仍然存在一些有待澄清的问题,计算结果的准确性也需要进一步的确认。本文承接上篇关于整圈阻尼长叶片频率计算的有限元方法,着重对叶片的应力分析过程中涉及的前处理以及求解过程中的参数设置进行了探讨,希望能够对叶片设计工程师的工作提供参考。     

拱型围带整圈连接叶片组固有频率计算和调频探讨

采用有限元法计算拱型围带的刚度并识别其与叶片连接处的边界条件，沿用叶片弯扭耦合振动和整圈连接传递矩阵理论，建立了拱型围带和拱型围带加松拉筋结构整圈连接叶片组固有频率计算模型方法。并比较了实物动，静频的计算和实测结果，表明二者吻合较好。对此类结构叶片的调频作了深入的研究，提出了调频方法。     

带有阻尼联接结构的汽轮机长叶片扭转恢复角的研究

本文利用空间梁模型，对带有阻尼结构的汽轮机扭曲长叶片的扭转恢复角进行了计算分析。在有限元方法的基础上，建立了叶片间阻尼联接结构的稳态分析模型，以探讨由此产生的耦合效应，为阻尼结构的进一步研究提供了一个理论计算基础。据此对８５１ｍｍ叶片进行了计算，获得了较为合理的结果。图１３参６     

长叶片和叶片组稳态应力及扭转恢复角的有限元法

本文采用空间扭曲梁单元,建立了一种用于扭曲长叶片和叶片组稳态应力及扭转恢复角计算的有限元法.并对某851mm长叶片进行了计算.图6参7     

单叶片强度分析及整圈叶片动频计算

根据国内外同行多年设计经验,综合考虑安全性、经济性与工艺性,设计了1200mm长叶片的结构。在此基础上,应用有限元方法,建立了单叶片的有限元模型,在3300 r/min超速运行条件下,分析了叶片的静应力。计算结果表明,在超速情况下叶片强度是安全的;应用有限元商用软件ANSYS,采用接触边界法,建立了整圈叶片模型,计算了整圈叶片的动频率,得到叶轮的三重点共振转速M3为2802 r/min,由于叶片的工作转速为2820 r/min~3 090r/min,因此在该区间无三重点共振,叶片振动是安全的。     

1 200mm叶片的非线性摩擦减振特性

根据国内外同行多年设计经验,综合考虑安全性、经济性与工艺性,设计了1200mm长叶片的结构,其中静叶为变截面空间三维弯扭联合成型叶片;动叶为考虑大变形、附加动应力最小的变截面空间反扭成型叶片;动叶的拉筋和围带设计成自带凸台拉筋和自带围带整圈软联接;叶根方案确定为斜四齿枞树型。在此基础上采用固定界面模态综合法计算了整圈叶片的非线性振动响应。设计与计算结果表明:采用自带凸台拉筋和自带围带整圈软联接结构形式的1200mm长叶片,在外激振力作用下,具有良好的摩擦减振性能。     

汽轮机长叶片扭转恢复特性研究

利用有限元分析软件ALGOR,建立基于三维实体模型的汽轮机长叶片扭转恢复特性计算与分析模型.并以国产1029mm叶片为研究对象,研究自由叶片、自带围带阻尼的叶片的扭转恢复特性.研究与分析表明,自由叶片与自带围带阻尼叶片的扭转恢复特性有较大的区别.自由叶片的扭转恢复特性与转速密切相关;自带围带阻尼叶片的扭转恢复特性不但与转速相关,而且与围带阻尼结构的结构参数有着密切的关系.     

长叶片约束予扭设计体系研究

简述了长叶片扭转恢复对叶片几何、气动、强度和振动产生的影响,并根据和或者睛的扭转恢复原理,采用叶片予扭和予扭装配的方法来肝解扭转恢复所带的负面影响,建立一种的和片设计体系－长叶片约束予扭设计体系。     

Reconstruction method for running shape of rotor blade considering nonlinear stiffness and loads

The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.     

Classical flutter analysis of composite wind turbine blades including compressibility

For wind turbine blades with the increased slenderness ratio, flutter instability may occur at lower wind and rotational speeds. For long blades, at the flutter condition, relative velocities at blade sections away from the hub center are usually in the subsonic compressible range. In this study, for the first time for composite wind turbine blades, a frequency domain classical flutter analysis methodology has been presented including the compressibility effect only for the outboard blade sections, which are in the compressible flow regime exceeding Mach 0.3. Flutter analyses have been performed for the baseline blade designed for the 5‐MW wind turbine of NREL. Beam‐blade model has been generated by making analogy with the structural model of the prewisted rotating thin‐walled beam (TWB) and variational asymptotic beam section (VABS) method has been utilized for the calculation of the sectional properties of the blade. To investigate the compressibility effect on the flutter characteristics of the blade, frequency and time domain aeroelastic analyses have been conducted by utilizing unsteady aerodynamics via incompressible and compressible indicial functions. This study shows that with use of compressible indicial functions, the effect of compressibility can be taken into account effectively in the frequency domain aeroelastic stability analysis of long blades whose outboard sections are inevitably in the compressible flow regime at the onset of flutter.     

运用现代CAE工具开发大容量汽轮机的关键部件——末级长叶片

末级长叶片是汽轮机机组的关键部件之一.汽轮机的效率和末级叶片的排汽面积(叶片高度)息息相关.近年来伴随着高参数汽轮机以及半转速大容量汽轮机在国内的推广应用,一系列长度为1 000 mm以上的全速长叶片以及1 600 mm至1 900mm等级的半速长叶片的开发都被提上了议事日程,其中1 710 mm叶片是一个已经实际开发成功的产品.以其为例对长叶片开发所涉及的方法,包括一些针对长叶片的新思路,进行阐述,重点对采用现代CAE工具开发长叶片的过程进行了论述.通过比较不同方法得到的计算结果以及试验结果,证明当前将商业CAE程序应用到长叶片的工程研发领域,可以同时满足精度和效率的要求.     

基于热流固耦合分析的重型燃气轮机透平高压叶片寿命研究

先进高效的重型燃气轮机透平高压叶片工作在高温、高压、高转速的严苛环境中,为了评估其安全可靠性,本文基于三维稳态粘性Navier-Stokes方程,考虑气动与热物理场的耦合,运用共轭计算技术和SST湍流模型建立了具有完整内外冷却结构的某燃气轮机高压透平叶片热流固耦合分析模型和寿命分析模型,获得了叶片温度分布及相应的应变应力场,并详细分析了叶片上热障涂层和金属基底的寿命状况。研究结果对理解和掌握先进的燃气轮机透平叶片设计技术具有重要参考意义。     

某型发动机低压二级叶片振动可靠性评估

鉴于某型发动机低压压气机二级叶片外场使用中损伤较多,应用振动可靠性评估的模糊方法和非概率方法对该级叶片进行振动可靠性评估。评估结果表明,该级叶片存在旋转失速激发的一阶弯曲振动共振导致的高周疲劳失效。     

Computational fluid dynamics simulation of the aerodynamics of a high solidity,small‐scale vertical axis wind turbine

A computational fluid dynamics simulation was performed for a small‐scale, high solidity (σ = 0.48) H‐type Darrieus vertical axis wind turbine. Two‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations were solved for the turbine numerical model, which has a large stationary domain and smaller rotating subdomain connected by a sliding mesh interface. The simulation results were first validated against steady‐state airfoil data. The model was then used to solve for three rotating blades with constant ambient flow velocity (Re = 360,000) over numerous blade speed ratios. The high solidity and the associated low blade speed ratio and rotational speed of the turbine result in complex flow–blade interaction mechanisms. These include dynamic stall resulting in vortex shedding, vortex impingement on the source blade and significant flow momentum extraction causing reduced power production from the downstream blade pass. Copyright © 2011 John Wiley & Sons, Ltd.     

湿蒸汽透平级水滴撞击动叶的频率及法向速度的研究

为了提高汽轮机湿蒸汽级叶片的可靠性,预防电厂中汽轮机叶片的水蚀疲劳断裂,建立了可求解动叶通道内湿蒸汽三维两相粘性可压缩湍流流场在旋转坐标系下的基本控制方程组,并将其应用于某汽轮机湿蒸汽透平级水滴运动的分析。给出了不同粒径水滴在动叶通道内的运动轨迹和单位撞击率。在此基础上详细分析了不同粒径水滴在动叶表面的法向速度分布。通过分析得出单位撞击率及撞击法向速度均高的“两高区域”为水蚀高发区。获得的相关定量数据为进一步研究液固撞击压力和动叶水蚀疲劳寿命提供了有力的依据。     

Numerical simulation of flow instabilities in high speed multistage compressors

INTRODUCTIONTheusefuloperatingrangeofturbomachinerycompressionsystemsislimitedbytheonsetoffluiddynamicinstabilities.Bothformsofinstabilities,rotatingstallandsurge,willdegradecompressionsystemperformanceanddurabilityll].naditionally,thisundesirablebeh...     

Numerical investigation of the unsteady tip leakage flow and rotating stall inception in a transonic compressor

<正>It is well known that tip leakage flow has a strong effect on the compressor performance and stability. This paper reports on a numerical investigation of detailed flow structures in an isolated transonic compressor rotor-NASA Rotor 37 at near stall and stalled conditions aimed at improving understanding of changes in 3D tip leakage flow structures with rotating stall inception.Steady and unsteady 3D Navier-Stokes analyses were conducted to investigate flow structures in the same rotor.For steady analysis,the predicted results agree well with the experimental data for the estimation of compressor rotor global performance.For unsteady flow analysis, the unsteady flow nature caused by the breakdown of the tip leakage vortex in blade tip region in the transonic compressor rotor at near stall condition has been captured with a single blade passage.On the other hand, the time-accurate unsteady computations of multi-blade passage at near stall condition indicate that the unsteady breakdown of the tip leakage vortex triggered the short length-scale-spike type rotating stall inception at blade tip region.It was the forward spillage of the tip leakage flow at blade leading edge resulting in the spike stall inception. As the mass flow ratio is decreased,the rotating stall cell was further developed in the blade passage.