Effects of combustor-level high inlet turbulence on the endwall flow and heat/mass transfer of a high-turning turbine rotor cascade

Experimental data are presented which describe the effects of a combustor-level high free-stream turbulence on the near-wall flow structure and heat/mass transfer on the endwall of a linear high-turning turbine rotor cascade. The endwall flow structure is visualized by employing the partial- and total-coverage oil-film technique, and heat/mass transfer rate is measured by the naphthalene sublimation method. A turbulence generator is designed to provide a highly-turbulent flow which has free-stream turbulence intensity and integral length scale of 14.7% and 80mm, respectively, at the cascade entrance. The surface flow visualizations show that the high free-stream turbulence has little effect on the attachment line, but alters the separation line noticeably. Under high free-stream turbulence, the incoming near-wall flow upstream of the adjacent separation lines collides more obliquely with the suction surface. A weaker lift-up force arising from this more oblique collision results in the narrower suction-side corner vortex area in the high turbulence case. The high free-stream turbulence enhances the heat/mass transfer in the central area of the turbine passage, but only a slight augmentation is found in the endwall regions adjacent to the leading and trailing edges. Therefore, the high free-stream turbulence makes the endwall heat load more uniform. It is also observed that the heat/mass transfers along the locus of the pressure-side leg of the leading-edge horseshoe vortex and along the suctionside corner are influenced most strongly by the high free-stream turbulence. In this study, the endwall surface is classified into seven different regions based on the local heat/mass transfer distribution, and the effects of the high free-stream turbulence on the local heat/mass transfer in each region are discussed in detail.     

浮式风机共享锚点系泊系统动力响应分析与成本评估

为提高海上浮式风机(Floating Offshore Wind Turbine, FOWT)的系泊效率和经济效益,以NREL 5 MW海上浮式发电机组OC3 Hywind系泊系统为研究目标,研究一种新型多系泊线共享锚点的系泊设计方式,即风电场中多个相邻风机共享锚点,将多线锚净力定义为作用在该锚上的系泊线张力的矢量和,并在SIMA RIFLEX软件中进行时域响应模拟,对多线共享锚点系泊系统进行动力响应分析和成本评估。结果表明：对于大规模海上风电场,采用3线和4线共享锚点的设计可使所需锚点的数量分别降低66.7%和75.0%;与传统的单线锚系泊相比,3线和4线共享锚点的设计均使多线锚载荷减小;对于风机数量为100个的大规模风电场而言,采用3线和4线共享锚点的设计可使风电场中锚的总成本分别降低55.94%和63.49%。该研究可为共享系泊设计在海上风电场中的应用提供参考。     

2.4m跨声速风洞涡轮动力模拟器安全监控系统

2.4m跨声速风洞涡轮动力模拟器安全监控系统,由系统板卡自检、通道校准、系统监控、数据分析及传感器系数数据库模块组成.其在安全联锁设计包括转速信号处理、加速度信号处理、过载保护、转换三通球阀等.应用结果表明,该系统满足跨声速风洞涡轮动力模拟器试验设备对安全监控系统的技术要求.     

Effect of Casting Modulus on Microstructure and Segregation in K441 Superalloy Casting

Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy (OM) and scanning electron microscopy (SEM). The micro-segregation was tested by energy dispersive spectroscopy (EDS) and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.16 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of Al increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of Al and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.     

28000m~3/h空分设备配套引进设备运行情况总结

介绍兖矿鲁南化肥厂28000 m3/h空分设备配套的进口液氧泵、液氮泵和透平膨胀机等引进设备的设计参数,分析在运行过程中出现的液氧泵电机烧坏、液氮泵汽蚀、液氮泵迷宫损坏和透平膨胀机轴振动值波动频繁等问题,叙述了处理问题的方法和措施。     

18MW汽轮风机油系统故障分析处理

针对汽轮鼓风机油系统存在的问题,分析原因并对其采取改进措施,确保高炉稳定生产.     

小间隙直通迷宫密封流场与泄漏特性数值模拟

采用RNGκ—ε模型对小间隙(<0.1 mm)直通迷宫密封可压缩定常湍流场进行数值模拟,得到通道内的速度、温度等流场典型分布。通过改变密封间隙、齿深等,得出通道内最大马赫数及泄漏曲线趋势图。结果表明小间隙时直通迷宫密封内存在齿尖节流、空腔膨胀及射流偏转、复热等主要特征,而小间隙下增加齿深会降低泄漏量。     

风力机叶片的弯扭耦合振动分析

根据一般粘性阻尼叶片的弯扭耦合振动模型,利用有限差分方法对叶片的动力方程进行离散处理,得到了叶片的质量、阻尼和刚度矩阵。然后运用MATLAB振动工具箱对系统的弯扭耦合振动进行了仿真分析,求出四种不同类型叶片的六阶固有频率和振型,并与相关文献进行了比较分析。在建立叶片系统的线性定常状态空间方程的基础上,对叶片施加初始位移扰动,通过运用时间离散和MATLAB振动工具箱,得到叶片在弯扭方向的收敛、颤振和发散振动仿真曲线。论文的研究对风力机叶片的设计生产有一定的借鉴意义。     

改进蜂群算法在风机变桨距控制中的应用

风力发电系统建模过程复杂,具有很强的非线性,受参数变化和外部干扰严重,且运行环境恶劣。因此,在控制器部分提出用自抗扰控制理论解决风力发电系统的变桨距控制问题,实现最大功率跟踪。并采用改进人工蜂群算法对自抗扰控制器的参数进行优化,解决其整定过程繁琐,具有很多不确定性的问题。MATLAB的仿真结果表明,优化后的控制器调整参数减少,简化了调节过程,弥补了人工蜂群算法搜索过程寻优速度慢,迭代后期容易陷入局部最优的不足,提高了优化精度。