打靶法在非线性转子—轴承系统中的应用

以转子动力学和非线性动力学理论为基础，针对非线性弹性转子－轴承系统的具体特点，用打靶法对采用短轴承模型的弹性转子－轴承系统的周期解进行了求解，并用数值积分和庞加莱映射方法对其动力学特性随某一参数变化时稳定性的改变进行了分析，计算结果表明，系统具有发生倍周期分叉及概周期运行的可能。用数值方法得到系统在某些参数域中的分叉图，直观显示了系统在某些参数域中的动态状态。数值分析结果为该类转子一轴承系统的设计和运行状态控制提供了理论参考。     

非线性刚性转子--轴承系统的分叉研究

以转子动力学和非线性动力学理论为基础,针对非线性转子——轴承系统的具体特点,用数值积分和庞加莱映射方法对采用长轴承模型的刚性Jeffcott转子轴承系统在较宽参数范围内进行稳定性研究。计算结果表明,系统存在Hopf分叉及低周期运动。用数值方法得到系统在某些参数域中的分叉图、响应曲线、频谱图、相图、轴心轨迹及庞加莱映射图,直视显示了系统在某些参数域中的运行状态;数值分析结果为该类转子─—轴承系统的设计和安全运行提供理论参考。     

非线性刚性转子——轴承系统的分叉研究

以转子动力学和非线性动力学理论为基础,针对非线性转子－－轴承系统的具体只分和庞加莱映身方法对采用长轴承模型的刚性Ｊｅｆｆｃｏｔｔ转子轴承系统在较宽参数范围内进行稳定性研究。计算结果表明,系统存在Ｈｏｐｆ分叉及概周期运动。用数值方法得到系统在某些参数域中的分叉图、响应曲线、频谱图、相图、轴心轨迹及庞加莱遇射图,直观显示了系统了系统在某些参数域中的运行状态、数值分析结果为该类子－－轴承系统的设计和安全     

非线性刚性转子_轴承系统的混沌研究

以转子的动力学和非线性动力学理论为基础,针对非线性转子－轴承系统的具体特点,用数值积分和庞加莱映射方法对采用短轴承模型的刚性Ｊｅｆｆｃｏｔｔ转子轴承系统在较宽参数范围内进行稳定性研究。     

非线性碰摩转子系统动力响应研究

建立了短轴承模型的非线性转子系统发生碰摩时的数学模型,结合数值仿真计算对碰摩转子所表现出的动力学特性进行研究,分析表明系统除具有各种形式的周期和拟周期振动以外,还具有丰富的混沌运动和分岔现象.用数值方法得到系统在某些参数域中的分岔图、轴心轨迹、庞加莱映射图、响应曲线和频谱图,直观显示了系统在某些参数域中的运行状态;同时研究了不平衡量对转子系统响应的影响,数值分析结果为该类转子系统的理论分析与故障诊断提供了参考.     

转子-轴承系统的非线性动力学的研究

对转子 -轴承系统的混沌运动进行动力学研究 ,采用非线性油膜力数据库方法获得椭圆轴承的非线性油膜力 ,数值计算得到了系统在某些参数域中的分叉图、轴心轨迹、相图、Poincar啨映射、时域波形和频谱图 ,直观显示了系统发生混沌运动的性态 ,用李雅普诺夫指数对混沌运动时的时间序列进行了判断 ,为控制转子系统混沌运动的发生及动力学设计提供了理论基础     

碰摩拉杆转子非线性动力学响应特性

对定点碰摩故障状态下拉杆转子的非线性动力学响应特性进行了研究.将轮盘之间的非线性接触特性等效为具有非线性抗弯刚度的弹簧,基于达朗贝尔原理建立了考虑轮盘之间非线性接触特性、非线性油膜力以及碰摩力作用的拉杆转子轴承系统运动方程,并采用数值积分方法对运动方程进行求解,分析了系统位移响应随轮盘的转速和碰摩刚度等参数变化的规律.结果表明:轮盘之间的非线性接触对系统位移响应特性影响较大;随着轮盘转速的升高,系统呈非线性特性;碰摩刚度是影响拉杆转子轴承系统运动状态的重要因素,若增大碰摩刚度,系统的运动状态将发生改变.     

不同油膜力模型下转子椭圆轴承系统的动力学分析

1引言滑动轴承的非线性油膜力模型是转子-轴承系统非线性动力学分析和研究的关键问题。滑动轴承的油膜力具有强烈的非线性特性,研究转子-椭圆轴承系统的非线性动力学问题关键在于获得椭圆轴承的油膜力模型。其中椭圆轴承的非线性油膜力的计算精度和计算速度将直接影响到转子-轴     

立式转子-轴承系统动力学特性研究

建立了立式转子-轴承系统的动力学模型,采用Newmark数值方法研究了不平衡量及轴承参数对立式转子-轴承系统的动力学特性和稳定性影响并与卧式转子系统进行了对比分析.结果表明:和卧式转子相比,立式转子由于载荷轻稳定性差,稳定性对参数的改变也更为敏感.通过改造Bently-RK4转子-轴承系统实验台,试验验证了上述立式转子与卧式转子的动力学特性差别.研究结果对于立式转子-轴承系统的设计和故障诊断具有一定的参考价值.     

轴承标高对多跨转子-轴承系统非线性稳定性的影响研究

建立了考虑转子-轴承标高与非线性油膜力的多跨转子-轴承系统高维非线性动力学模型。利用固定界面模态综合法对该模型进行降维,采用Newmark逐步积分法对降维后的动力学模型进行数值计算,可得到转子在各种标高情况下发生油膜失稳的转速门槛值和轴承标高变化对系统动力稳定性的影响规律。对200MW汽轮发电机组转子-轴承系统计算分析表明：由于低压转子后轴承的标高抬起,将导致发电机转子前轴承轴颈的失稳转速显著提前,系统的稳定性降低。分析结果从理论上解释了电站200MW汽轮发电机组发电机前轴承处转子易发生油膜失稳的原因,并且证明了本文所提出方法的有效性。     

上海引进型300MW机组发电机-励磁机振动特性综述

上海引进型300MW机组存在工作转速下励磁机振动不稳定问题.首次改进后引起临界转速区域发电机与励磁机振动响应过高问题.第二次改进后采用静态励磁方式,彻底解决了因设计原因引起的该型机组发电机-励磁机振动问题.基于现场实测数据及转子动力学理论,讨论及总结该型机组发电机-励磁机振动机理和特性.     

转子中心孔修磨机的设计与应用

介绍了转子中心孔修磨机的设计原理及应用。     

切向永磁电机转子整体斜极方法及其对转矩脉动的影响

切向结构电机谐波含量丰富,转矩脉动较大,转子斜极可有效降低电机转矩脉动。文中针对切向结构永磁电机,使用不分段转子整体斜极方法来抑制电机的转矩脉动,并通过有限元分析软件对比了对称结构与斜极结构的各种性能表现,并试验验证了转子斜极结构能够有效改善电机的转矩脉动。     

汽轮机焊接转子接头残余应力研究三:125MW及1000MW汽轮机低压焊接转子产品残余应力

在测试转子模拟件外圆、内圆、剖面处热处理前后的残余应力分布的基础上,在研究弹性槽对根部打底焊缝处残余应力的影响以及盖面焊缝下方4～5层焊道处残余应力的分布的基础上,测试了125 MW及1 000MW实际火电低压焊接转子接头处的残余应力.结果表明,实际产品残余应力的分布与模拟件相似,数值更小;不同结构均承受- 120 MPa左右的轴向压缩应力,切向应力可被忽略.相关结果对掌握焊接转子残余应力分布提供了重要参考.     

Performance investigation of a small Savonius-Darrius counter-rotating vertical-axis wind turbine

This paper describes the study of a small vertical-axis wind turbine (VAWT) with a combined design of Darrius and Savonius counter-rotating rotors. The main purpose of this study is to improve the extraction capabilities of a single-rotor VAWT by using two distinct rotor designs while adopting the counter-rotating technique. Given that the conversion capabilities and operational speed of the existing wind turbines are still limited, the current technique is used to enhance the efficiency and expand the operating wind speed range of the VAWT. The Darrius and Savonius counter-rotating rotors were exposed to a similar upstream wind speed using a centrifugal blower. It was found that the Savonius-Darrius counter-rotating rotor was able to operate effectively, particularly at the low-speed wind. By looking at the individual performance of the rotors, it was observed that the conversion efficiency of the H-type rotor increases as the wind speed increases. However, in the case of the S-type rotor, it is higher at lower wind speed and tends to decrease as the operating speed increases. Thus, the maximum efficiency of the S-type rotor was achieved at low speed, whereas the H-type rotor has achieved its maximum efficiency at the highest operating wind speed. The average efficiency of the present Savonius-Darrius counter-rotating rotor has been improved to reach almost 42% and 30% more efficiency in terms of torque and power, respectively.     

Design of a wind turbine rotor for maximum aerodynamic efficiency

The design of a three‐bladed wind turbine rotor is described, where the main focus has been highest possible mechanical power coefficient, CP, at a single operational condition. Structural, as well as off‐design, issues are not considered, leading to a purely theoretical design for investigating maximum aerodynamic efficiency. The rotor is designed assuming constant induction for most of the blade span, but near the tip region, a constant load is assumed instead. The rotor design is obtained using an actuator disc model, and is subsequently verified using both a free‐wake lifting line method and a full three‐dimensional Navier–Stokes solver. Excellent agreement is obtained using the three models. Global CP reaches a value of slightly above 0.51, while global thrust coefficient CT is 0.87. The local power coefficient C_p increases to slightly above the Betz limit on the inner part of the rotor; the local thrust coefficient C_t increases to a value above 1.1. This agrees well with the theory of de Vries, which states that including the effect of the low pressure behind the centre of the rotor stemming from the increased rotation, both C_p and C_t will increase towards the root. Towards the tip, both C_p and C_t decrease due to tip corrections as well as drag. Copyright © 2008 John Wiley & Sons, Ltd.     

Actuator line/Navier–Stokes computations for the MEXICO rotor: comparison with detailed measurements

In the European collaborative MEXICO (Model Experiments in Controlled Conditions) project, a series of experiments was carried out on a 4.5 m diameter wind turbine rotor to validate numerical diagnostics tools. Here, some of the measured data are compared with computations of the combined actuator line/Navier–Stokes (AL/NS) model developed at the Technical University of Denmark. The AL/NS model was combined with a large eddy simulation technique and used to compute the flow past the MEXICO rotor in free air and in the DNW German‐Dutch wind tunnel for three commonly defined test cases at wind speeds of 10, 15 and 24 m s ^?1. Two sets of airfoil data were used. Comparisons of blade loadings showed that the AL/NS technique with the modified airfoil data is in better agreement with the measurements than with the original 2D airfoil data. Comparisons of detailed near‐wake velocities showed good agreement with the measurements. Computations including the influence of the geometry of the wind tunnel showed that tunnel effects are not significant and the effect of the geometry of the wind tunnel only results in a speedup of 3% at a thrust coefficient of C_T = 1.Copyright © 2011 John Wiley & Sons, Ltd.     

几种材料和结构的轮盘转子破裂准则的试验应用

本文叙述了对用于火箭、直升机、运输机的燃气涡轮发动机及船用高速柴油机增压器的锻、铸造耐热合金、高强度铝合金的不同结构轮盘转子破裂准则所作的预先确定;在旋转试验台上进行的轮盘转子破裂试验。成功地证明了几种破裂准则(包括K1c 准则)对不同材料和结构,的轮盘转子的适用性。     

密封系统对某压缩机转子振动影响的研究

利用数值分析的方法,研究了密封系统对某压缩机转子振动的影响效果。分析结果表明,密封对转子的振动有非常明显的影响,密封是否会引起转子失稳,主要取决于转子的转速、密封的交叉刚度系数和主阻尼系数,只有转速达到特定值,同时交叉刚度的影响大于阻尼的影响时,转子才会失稳;转子各级叶轮处的密封对转子振动的影响程度不同,以中间一级叶轮的影响最为显著。