Modal characteristics and fatigue strength of compressor blades

High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. The modal characteristics and endurance strength of a 5 MW gas turbine engine blade developed by Doosan Heavy Industries & Construction Co., Ltd. in HCF fracture were verified through analysis and tests to determine the reliability of the compressor blade. A compressor blade design procedure that considers HCF life was performed in the following order: airfoil and blade profile design, modal analysis, stress distribution test, stress endurance limit test, and fatigue life verification. This study analyzed the Campbell diagram and estimated resonance risk on the basis of the natural frequency analysis and modal test of the compressor blade to guarantee safe and operational reliability. In addition, the maximum stress point of the compressor blade was determined through stress distribution analysis and test. The bonding point of the strain gage was determined by using fatigue test. Stress endurance limit test was performed based on the results of these tests. This research compared and verified the modal characteristics and endurance strengths of the compressor blades to prevent HCF fracture, which is among the major causes of gas turbine engine damage. A fatigue life design procedure of compressor blades was established. The 5 MW class gas turbine compressor blade is well designed in terms of resonance stability and fatigue endurance limit.     

车轮径向疲劳试验有限元仿真及疲劳寿命估算

采用有限元分析方法,建立汽车车轮有限元模型,模拟车轮径向疲劳试验施加合理的载荷及边界条件.通过分析车轮试验过程中的应力变化情况,得出高应力集中区域及其各主应力值,运用疲劳寿命计算理论及ANSYS软件估算车轮的疲劳寿命.通过与车轮径向疲劳试验结果进行比较,结果表明高应力集中区域与实际裂纹位置吻合,预估的疲劳寿命与车轮实验寿命基本吻合,验证了有限元方法预估车轮寿命的有效性,为以后对车轮进行结构改进起指导作用.     

Identification of low-pressure compressor blades flutter

The unstable oscillations during coaxial low-pressure compressor blade flutter has been examined. The spectral analysis of strain gage records of blade oscillations and synchronous records of pressure pulsations in the countercurrent air flow shows that the damping of oscillation modes is the most informative parameter defining the flutter’s evolution process. The coincidence of the eigenfrequencies of the blades and the synchronous character of the changes in the time relationships of damping at the eigenfrequencies frequencies of the blade, and at the frequencies of acoustic diametrical modes of pressure pulsations occurring in the air flow shows that the phenomenon of flutter relates to the blades collective oscillation.     

Reliability and fatigue life evaluation of railway axles

The axle is one of the most important components of a rail vehicle which transmits the weight of the vehicle to the wheels, meets the vertical and horizontal loads formed during static and dynamic moving, and carries the driving moment and braking moment. The prediction of fatigue failure of axles plays an important role in preventing fatigue fractures. Varying loads on components lead to cumulative failure in the mechanism. In this study, failures in axles of rail vehicles serving the Istanbul Transportation Co. have been investigated. Statistical evaluation of real life values has been performed by taking into account the kilometer and load cycle. Equivalent stresses have been used to derive life equations and diagrams by using one of the cumulative life theories known as the Palmgren-Miner method. Finally, theoretical and practical Wohler diagrams S-N (σ-N: stress-life) have been plotted to reveal error calculation.     

空气压缩机透平机叶片结垢原因分析及解决措施

介绍了中国石化股份有限公司九江石化公司化肥装置空气压缩机组和氮气压缩机组的透平机叶片结垢的原因和危害。采用低温低压饱和湿蒸汽清洗去除叶片结垢。在生产运行中加强水质监督,保证蒸汽品质,取得了明显的效果,解决了机组运行存在的问题,从而提高了机组的运行效率,保障了机组高效、安全、稳定和经济运行。     

Impact evaluation of rolling contact fatigue life models

Since the accurate prediction of fatigue life has a significant value, many researchers have attempted to develop a reliable fatigue life model. Recently, rolling contact fatigue life models incorporating machining impact were developed. These models have contributed to a significant improvement in prediction accuracy as compared with earlier models, thus representing a major step forward in the modeling effort. This paper compares the prediction accuracy of these models with that of the prediction method in International Standards. When α is set to 0.25, the observed improvement of prediction accuracy as measured by variance of prediction errors due to these models over that due to prediction method in International Standards is statistically significant. Impact analyses of such improvement are conducted to illustrate its value. It is further noted that while difference was observed between the variance of prediction errors due to the crack initiation life model based on a dislocation model and that due to the crack initiation life model based on a local stress-life curve, the observed difference is not statistically significant.

     

压缩机叶片动静态特性研究方法的进展

叶片是压缩机的关键性部件之一,其结构设计的合理程度主要体现于叶片的静、动态等特性,这些特性的优劣会直接影响压缩机的整体性能。根据近年来国内外研究叶片动静态特性的状况,结合理论与事实,将理论分析、实验研究和数值计算三类方法进行了对比分析,得出数值计算方法是研究叶片动静态特性的一种有效途径,可以方便获得叶片的静力和动力特性参数,为优化设计叶片结构提供理论数值参考。相对理论分析和实验研究方法而言,数值计算方法具有直观形象、应用范围广、灵活方便等优点。     

超高压压缩机脉冲阀螺栓疲劳寿命分析

超高压压缩机脉冲阀螺栓在交变载荷作用下,使用一段时间后可能会产生疲劳失效破坏.文中介绍了脉冲阀螺栓疲劳寿命的分析方法,利用裂纹扩展速率与螺栓的临界裂纹尺寸对含缺陷的螺栓疲劳寿命进行了计算,为设备的诊断维护提供了合理的依据.     

3W2型高压力压缩机机构动力学分析及曲轴疲劳研究

针对压缩机压力的大幅度提高所带来的压缩机核心部件曲轴的强度分析问题,对压缩机机构进行了动力学分析及曲轴疲劳研究。首先基于多刚体系统相关理论建立了曲柄连杆活塞机构多刚体模型,使用ADAMS对其进行了运动学仿真,得出了活塞某一时刻的位移、速度、加速度值,然后与活塞此刻的理论计算结果进行对比,发现两者的误差都在允许的范围内,进而对其进行了动力学仿真,得出各连杆轴颈所受到的交变载荷,为下面曲轴的疲劳分析提供基础。最后对其关键部件曲轴进行了静态特性分析,在交变载荷的作用下完成其静态强度和疲劳强度的校核。研究结果表明,从应力曲线图与应力幅值曲线图中得出其安全系数均在许用范围内,证明其强度满足设计要求。     

轴流式压缩机叶片有限元分析模型的建立

压缩机叶片是由复杂的自由曲面包络而成的零件,在对其做应力分析之前需进行有限元建模.提出在获得了ANSYS下叶片的实体几何模型的基础上,考虑到叶片实体几何模型的复杂性,为了很好地对叶片进行离散,采用三维实体单元Solid187对叶片进行网格划分.同时为了确保计算精度,将叶片分割成叶型和叶根两部分,分别对其划分网格,然后再...     

Design optimization of axial flow compressor blades with three-dimensional Navier-Stokes solver

Numerical optimization techniques combined with a three-dimensional thin-layer NavierStokes solver are presented to find an optimum shape of a stator blade in an axial compressor through calculations of single stage rotor-stator flow, Governing differential equations are discretized using an explicit finite difference method and solved by a multi-stage Runge-Kutta scheme. Baldwin-Lomax model is chosen to describe turbulence. A spatially-varying time-step and an implicit residual smoothing are used to accelerate convergence. A steady mixing approach is used to pass information between stator and rotor blades. For numerical optimization, searching direction is found by the steepest decent and conjugate direction methods, and the golden section method is used to determine optimum moving distance along the searching direction. The object of present optimization is to maximize efficiency. An optimum stacking line is found to design a custom-tailored 3-dimensional blade for maximum efficiency with the other parameters fixed.     

Physical phenomena in the polishing of compressor blades for gas-turbine engines

Russian Engineering Research -     

基于IPC的汽车悬架疲劳寿命试验台设计

针对汽车悬架疲劳寿命检测,设计了悬架疲劳寿命试验台装置,该试验台由动态试验与静态试验装置构成.采用研华IPPC-6172A工控机作为核心控制计算机,结合研华PCIE-1812数据采集卡实现电机驱动系统、液压举升系统、负载系统的测量与控制.采用Visual C++2015设计该试验台控制软件,Microsoft Acce...     

Fatigue life evaluation of mechanical components using vibration fatigue analysis technique

Unit brackets attached on a cross member and subjected to random loads often fail due to self-vibration. To prevent such failures, it is necessary to understand the fatigue failure mode and to evaluate the fatigue life using test or analysis techniques. The objective of this study is to develop test specifications for components, which are applicable to predict fatigue life at the stage of initial product design, for the unit brackets by using a vibration fatigue technique. For this objective, the necessity of a fatigue analysis considering resonant effect was reviewed. Also, a series of vibration fatigue analyses were carried out by changing the acceleration’s direction and magnitude. Then, a methodology was proposed to determine the optimum vibration fatigue test specification of the component, which gives an equivalent failure mode with the vehicle test condition.     

电驱动换挡机构疲劳寿命试验系统设计

根据电驱动换挡机构疲劳寿命试验要求,设计开发了基于电驱动换挡机构疲劳寿命为评价指标的试验系统;并就系统的组成、工作原理和测控软件等进行了详细介绍。经试验验证,该系统稳定可靠,操作方便,很好地满足了电驱动换挡机构疲劳寿命试验的要求。目前,该系统已在多款电驱动换挡机构研发阶段取得了良好的应用效果。     

钢制车轮动态弯曲试验疲劳寿命预测

建立了钢制车轮动态弯曲疲劳试验的有限元静力学模型,分析了试验条件下一个载荷循环的结果响应,得到了八个载荷步的疲劳损伤载荷.基于Ansys/Fe-safe耐久性分析软件,用多轴临界面疲劳损伤模型,采用Brown-Miller准则,预测了车轮弯曲试验疲劳寿命.结果表明车轮动态弯曲疲劳试验性能满足要求,但疲劳安全系数不高.给出了改进设计的建议.     

Concerning the possibility of examining compressor blades according to attenuation and speed of ultrasound

Possibilities for studying the structural condition of the material, from which the operating blades of the axial compressor of a gas-turbine engine are made, are considered based on measuring ultrasound attenuation and speed. The results of measuring the propagation of pulses of longitudinal and elastic shear waves in the blade material after their operation and repair. The experimental studies are performed using an ultrasonic echo method. The potential of the nondestructive acoustic method of evaluating the structural state of corrosion resistant stainless steel after use, restorative repairs, and repeated use of the blades in the General Electric MS 5142 gas turbine engine of a GTK-25I gas compressor is presented.     

基于可靠性评价的超高压压缩机二段出口螺栓疲劳寿命预测

超高压压缩机螺栓在交变载荷作用下,会产生疲劳失效破坏.对两种工况下超高压压缩机二段出口螺栓进行了受力分析、断裂分析、疲劳分析与剩余寿命评估;利用裂纹扩展速率与螺栓的临界裂纹尺寸对含缺陷的超高压压缩机二段出口螺栓两种工况下疲劳寿命进行了预测,为设备的诊断维护提供了合理的依据.     

驱动桥桥壳疲劳寿命预测与试验

主要介绍电液伺服系统控制的驱动桥桥壳垂直弯曲疲劳强度试验台装置的结构及设计原理.同时采用CATIA三维造型软件建立驱动桥桥壳的3D模型,利用限元分析方法对该桥壳进行模拟分析.本文通过将桥壳台架试验和桥壳有限元模拟两种方法得出的结果进行对比分析研究,二者的结果基本一致,从而验证了有限元方法对桥壳疲劳寿命预测的可行性.把以上两种方法分别应用于桥壳设计生产的不同阶段,可以大大提高工作效率,保证出厂桥壳产品的工作可靠性.