Development of low-noise drag-type vertical wind turbines

In this study, the aerodynamic noise characteristics of Savonius wind turbines were investigated using hybrid computational aero-acoustics techniques, and low-noise designs were proposed based on the understanding of the noise generation mechanism. First, the flow field around the turbine was analyzed in detail by solving three-dimensional unsteady incompressible Reynolds-averaged Navier–Stokes equations using computational fluid dynamics techniques. Then, the aerodynamic noise radiating from the wind turbine was predicted using the Ffowcs Williams and Hawkings equation with the obtained flow field information. Two distinct harmonic noise components—the blade passing frequency (BPF) and harmonics with a fundamental frequency that is much higher than the BPF—were identified in the predicted noise spectrum. The origin of the higher harmonic components was found to be related to vortex shedding from the rotating turbine. Based on this finding, the proposed low-noise design for Savonius wind turbines uses S-shaped blades. S-shaped blades were found to reduce the noise levels of Savonius wind turbines by up to 2.7 dB.     

An Extraction of the Dominant Rotor-Stator Interaction Modes by the Use of Proper Orthogonal Decomposition （POD）

The Proper Orthogonal Decomposition method is applied to the instantaneous velocity field within the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor. The processed data come from experiments and numerical simulations. In comparison with a Fourier transform, the POD gives the best modal approximation for both initial fields, in terms of the energy expressed on any given number of modes to be taken into account: to reach 98% of the total energy of the velocity field, the required number of POD modes is around nine times smaller than the number of Fourier harmonics. The individual POD modes are given and show that the unsteady rotor-stator interaction is already present in the very first modes.     

汽轮发电机组转子及轴系弯扭耦合振动发展现状与展望

随着汽轮发电机组容量增大,轴系增长,在役运行时间增加,转子部分多数会有质量偏心现象出现,这使得转子轴系的扭转振动与弯曲振动的耦合作用明显增强。从弯扭耦合的角度来研究汽轮发电机组轴系的振动,将能更准确地把握轴系的动力学特性。总结了近年来国内外对汽轮发电机组转子及轴系弯扭耦合振动问题的研究进展和成果,并对其进一步研究进行了展望。弯扭耦合振动的研究对汽轮发电机组的安全运行和故障诊断都具有十分重要的意义,进一步的深入研究必须与力学学科一系列前沿问题研究相结合。     

裂纹转子的实验研究

对刚支裂纹转子、具有弹性支承的裂纹转子、刚支无裂纹转子以及具有弹性支承的无裂纹转子的振动特性进行了实验研究。研究表明：刚支裂纹转子和具有弹性支承的裂纹转子均发生分数次共振现象,且增加支承弹性有助于减小谐波共振。     

精炼30Cr2Ni4MoV低压转子材料在超超临界机组上的应用

采用Ansys有限元方法计算了超超临界机组低压转子的温度场,并整理了精练30Cr2N i4MoV低压转子材料的物理化学特性。通过对两者的分析对比,认为超超临界机组的低压转子采用精练30Cr2N i4MoV完全可以满足设计要求。     

Unigraphics NX、Vericut在汽轮机转子车削加工中的应用

汽轮机转子的数控加工目前主要通过手工编程来完成,通过运用Un igraph ics NX软件完成转子车削加工过程以及使用vericut软件对加工过程的仿真,验证应用Un igraph ics NX软件实现数控机床编程自动化的可行性。     

鼓风机轴系振动故障诊断及治理

本文通过对某钢铁公司3#鼓风机1#瓦发生乌金碎裂的原因分析,阐述了碎瓦故障的机理。通过分析提出,汽轮机对轮瓢偏超差和风机转子局部裂纹是导致1#瓦产生乌金碎裂和不稳定的主要原因。针对该机组奇特的振动现象描述了故障征兆,提出了消振措施及其故障排除方法,对类似机组的故障诊断有指导意义。     

交流电动机转子槽漏磁导数值积分计算

本文提出一种交流电动机转子槽下部漏磁导的数值积分计算方法。与传统的漏磁导算法相比,这种方法省去了推导漏磁导计算公式的繁琐过程,而直接从磁导概念出发,利用数值积分计算给出漏磁导数值。文中提出的方法对电机漏磁导的计算具有普遍意义。     

汽轮发电机的一类动力平衡问题

本文讨论了汽轮发电机组转子的次临界转速的若干动力平衡问题,着重指出卧式转了抗弯刚度的方向性是产生次临界转速的主要原因,同时也对次临界转速所引起的振动给出了稳定性判据.     

300MW汽轮发电机组断油烧瓦事故的原因分析及处理

介绍了某电厂3号汽轮发电机组断油烧瓦的经过和处理过程,分析了事故的原因。事实证明,闷缸措施可防止汽轮机转子永久性弯曲。