干式铁芯串联电抗器运行后的噪声问题分析及处理对策

对干式铁芯串联电抗器运行后出现的各种噪声进行了详细的分析,介绍了故障检测和处理的过程,为避免类似故障的发生,提出了相应的预防措施。     

干式空心电抗器匝间短路故障暂态特性仿真研究

从理论上分析了干式空心电抗器从正常运行状态到匝间短路故障状态下的匝间短路动态过程,建立了暂态电路耦合计算模型,并利用ANSYS Maxwell软件模拟了匝间短路故障的暂态特性,提出了通过安装在电抗器封装上的检测线圈实现对电抗器短路位置引起的磁场突然变化的检测方法。通过实验研究表明,采用本文提出的方法可以在较早的故障期间检测到匝间短路故障。     

干式铁芯电抗器线圈局放试验装置研究

分析了干式铁芯电抗器成品局放试验困难的原因,对线圈局放试验装置进行了讨论。     

干式变压器振动特性的研究及隔振系统的设计

针对位于居民区的干式变压器在运行时会产生振动,给周围居民带来噪声污染的问题,以SCB10-800型号的干式变压器为例,对其产生的振动进行监测和振源分析,使用ANSYS进行有限元模型的搭建,对干式变压器振动的特性进行了研究,为隔振系统的设计奠定了基础。最后,考虑到实际生产工作情况,提出了板-梁-质量隔振系统来降低变压器高频区域的振动传播。     

液压颤振器的流固耦合振动研究

介绍了一种液压颤振器的结构和工作原理,采用ANSYS Workbench、CFX和AMESim联合仿真,对颤振器流固耦合振动进行了CFD数值模拟,分析了颤振过程中的耦合场。实验研究发现,单作用颤振液压缸的流固耦合振动与双作用液压缸颤振结果有较大区别。     

耦合振动对传动系统影响的仿真研究

基于MSC.ADAMS软件,初步探讨了系统动力学模型的建立及仿真问题。主要利用三维实体造型工具UG和多体动力学仿真工具MSC.ADAMS建立了750 kW风力机组系统多刚体模型,对故障率较高的齿轮进行啮合力仿真分析,对齿轮箱故障进行了预测。     

基于ANSYS Workbench的输液管道系统振动控制仿真研究

以折弯式管道为例研究了输液管道系统的振动控制。首先,建立了输液管道系统的运动方程,但由于方程在离散过程中结构矩阵和流体矩阵的数值计算量过大,在计算过程中常出现溢出错误,因此使用模态缩减法简化矩阵以便于进行计算;其次,在高频振荡流体载荷的作用下,利用ANSYS Workbench的双向隐式迭代法计算管道系统的动力学特性;最后,建立带有节流孔板的管道系统有限元模型,研究了节流孔板对系统振动的抑制作用。计算结果表明节流孔板对输液管道系统的振动控制是非常有效的。     

基于振动能量的设备状态评价方法研究

论研究单自由度系统强迫振动时振动能量与振动疲劳寿命之间关系,然后用ANSYS/FE-SAFE软件对简支梁进行横向弯曲振动疲劳分析,结果表明,在一定范围内,振动能量越大,振动疲劳寿命越短,反之亦然,因此可以用振动能量对设备状态进行评价。对于测得的速度信号,可通过时域或频域积分的方法求得位移进而得到振动能量,也可以对信号进行频谱分析得到各频率下的幅值从而求得振动能量,后者更加方便准确。最后使用健康度定量描述设备的健康状态。     

基于弹炮刚柔耦合接触/碰撞的炮口振动研究

为了研究弹丸和身管膛线接触/碰撞对炮口扰动的影响,建立了身管膛线的三维实体模型,并在ADAMS中建立了基于接触/碰撞的弹炮刚柔耦合数值仿真模型,对该模型进行了数值仿真求解,仿真结果反映了炮口的振动特性;根据数值仿真结果分析了弹炮接触/碰撞对炮口振动的影响。仿真结果表明弹炮接触/碰撞对炮口振动的竖直方向的速度和位移、横向的速度和位移均有一定影响,从而影响火炮射击精度。     

脉动态电解加工多场耦合仿真分析及试验研究

为了掌握脉动态电解加工多物理场耦合机制,针对直流电解加工和脉动态电解加工两种加工模式建立了包含电场、流场、传热和气泡的数学模型来开展多物理场耦合仿真分析,研究不同加工间隙下多物理场耦合作用对电流密度分布的影响,通过试验对仿真结果进行了验证。     

控制系统中噪声作用机理及抗干扰措施研究

本文从控制理论的角度分析噪声干扰作用于控制系统的机理,以及通过滤波器衰减干扰信号的过程.进而提出控制系统的抗干扰措施,并以基于PLC和变频器的控制系统为例进行实证分析.     

起重机圆截面杆件横风向振动抑制结构的分析研究

岸边起重机结构中有许多长的弹性圆截面杆件,自振频率比较低,很容易发生横风共振。分析引起这类杆件振动的原因,介绍一些抑制风致振动的结构振动控制方法及相应的控振措施。提出利用抗扰条肋抑制此类风致振动的方法,并通过试验方法模拟了圆截面杆件的风致振动,取得一定的振动抑制效果。     

Structural vibration control for broadband noise attenuation in enclosures

This paper develops and evaluates several strategies for structural vibration control with the objective of attenuating broadband noise inside a rectangular enclosure. The strategies evaluated include model-independent collocated control, model-based feedback control and a new “modal-estimate” feedback strategy. Collocated control requires no knowledge of model parameters and enjoys the advantage of robustness. However, effective broadband noise attenuation with colocated control requires a large number of sensor-actuator pairs. Model-based controllers, on the other hand, can be theoretically effective even with the use of a single actuator. However, they suffer from a lack of robustness and are unsuitable from a practical point of view for broadband structural vibration applications where the dynamic models are of large order and poorly known. A new control strategy is developed based on attenuating a few structural vibration modes that have the best coupling with the enclosure acoustics. Broadband attenuation of these important modes can be achieved using a single actuator, a limited number of accelerometers and limited knowledge of a few modal functions. Simulation results are presented to demonstrate the effectiveness of the developed strategy.     

Diagnosis and control of machine induced noise and vibration in steel construction

Most high-rise buildings constructed of steel or steel reinforced concrete have to install various vital equipments. Among these equipments machinery noise is especially annoying for accommodation close to them. In attempting to control the machine-induced structure-borne noise and vibration, the methodology by employing mobility functions to identify the dominant frequency band of vibrational power flow transmission and to assess the isolation effectiveness of isolators is established. The proposed method of diagnosis procedure is applied to the structure-borne vibration power flow transmission for a steel construction parking tower. After proper check and replacement of the isolators of the power unit platform of the mechanical parking tower, the improvement results in a substantial structure-borne noise reduction of 16 dB(NC). The unique parts of the paper include the establishment of the relation of mobility functions with respect to four-pole parameters for a coupled machine/mount/foundation system. Also expressions to represent the vibrational input power, the output power and the transmitted power in relation to mobility functions are clarified. This paper was recommended for publication in revised form by Associate Editor Seong-Wook Hong Wei-Yu Lu received his Ph.D. degree from the Department of Systems Engineering and Naval Archi-tecture at the National Taiwan Ocean University. Wei-Hui Wang is a Professor Emeritus and Director at the Sound and Vibration Research Center, Department of Systems Engineering and Naval Architecture, National Taiwan Ocean University. He received his Ph.D. degree from the Depart-ment of Mechanical and Marine Engineering at the University of Plymouth, UK.     

基于SVD降噪的机械振动信号经验模式分解及其应用

提出了1种基于奇异值分解降噪的振动信号经验模式分解方法,利用该法对原始振动信号进行相空间重构和奇异值分解,并根据奇异值降噪,再利用经验模式分解法提取降噪后振动信号的基本模式分量,对滤波前和滤波后振动信号进行经验模式分解分析。分析结果表明：奇异值分解能有效地提高信噪比,突出原始振动信号的特征,使降噪后振动信号分解出的基本模式分量具有更明确的物理意义,有利于对柴油机进行精确诊断。     

船用汽轮机调节阀减振降噪研究与进展

介绍了国内外船用汽轮机调节阀减振降噪研究的现状,分析了国内产品技术开发中存在的不足,提出了船用低噪声阀门设计、生产和科研的发展方向。     

Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

Model errors in multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. In this paper, a combination of high-authority control (HAC) and low-authority control (LAC) is considered for improved performance in case of such model errors. A digital implementation of a control system is presented in which the HAC (adaptive MIMO control) is implemented on a CPU and in which the LAC (decentralized control) is implemented on a high-speed Field Programmable Gate Array. Experimental results are given which demonstrate that the HAC/LAC combination leads to performance advantages in terms of stabilization under parametric uncertainties and reduction of the error signal.     

基于压电执行器的切削振动主动控制实验研究

利用压电执行器,构造了切削振动主动控制实验系统并分析了该系统的控制机理;该系统根据以振抑振的思想,采用位移反馈策略对切削过程的振动行为进行干预,进而实施对振动的主动控制.从实验结果看,达到了明显的减振效果,该系统为将来制作更具商业前景的智能刀杆奠定了良好的基础.     

卧式车床车削振动主动控制系统设计与实验研究

分析了车削加工时振动的一般模型,并根据不同车削振动来源建立了它们各自的振动力与振动位移关系模型.针对机床运动失衡下的周期性振动,提出了一种振动主动控制方法.设计了基于PID控制算法与超磁致执行器的车削振动主动控制系统.通过数字仿真与现场试验,表明所设计的车削振动主动控制系统能有效地降低车削振动,提高车削加工精度.     

电抗器减振系统计算分析

为了解决某变电站电抗器设备振动噪声过大的问题,采用有限元数值仿真方法,建立了电抗器设备的有限元分析模型,应用ANSYS软件对其进行了模态和谐响应分析,得到了设备产生振动噪声的主要原因,即电抗器基础未能隔振产生并且由低频噪声引起。由此提出了在基座和设备之间增加橡胶隔振器的改进方法,通过与原设备对比分析可以证明,改进的隔振结构减振降噪效果明显。