The reduction of the vibration level in high-speed rotor systems by means of floating seal rings

The dynamics of high-speed rotor systems is studied during the rotation of the rotor in floating seal rings considering the effects of the hydrodynamic interaction forces between the rotor and the seal rings. A dynamic analysis of the “flexible-rotor-hydrodynamic-medium-floating-rings” system shows that the floating seal ring becomes a broad-band hydrodynamic oscillation damper when the rotor speed coincides with the partial frequency of the ring. Under transient conditions, it is practical to vary the speed slowly during the speedup/shutdown. The effect of the hydrodynamic forces also leads to the disappearance of the rotor critical speed since the rotor’s stiffness increases on the hydrodynamic layer more rapidly than the speed. The parameters of the seal rings of a multi-mass rotor system of turbo-driven pump assemblies for liquid-propellant rocket engines, such as the pressure drop and the masses, that ensure the damping of the oscillations are found.     

高速压力机机身减振的研究

为减小计算时间及保证计算精度,取机身模型的1/4进行处理和分析,分别赋予机身材料为Q235和铸铁,通过有限元瞬态分析得到机身立柱上A点的动态应力和位移响应,并对比其响应幅值和衰减速度,分析其减振效果.再分别设置拉紧螺杆的预紧力为1.5倍和2倍公称力,观察其减振效果,找到合适的材料和预紧力.最后利用振动及动态信号采集分析仪器采集A点在相应工况下的动态应力,验证分析的正确性和可行性,减小了高速压力机的振动影响,并应用于生产.     

高速轨道衡简介

作者依据十几年前国外发达国家研制高速轨道衡时的相关资料,介绍了在设计高速轨道衡中,应该考虑的几个问题和对干扰测量结果的各种信号的处理方式。     

Study of the influence of geometrical and mechanical parameters on ballasted railway tracks design

This paper investigates the vertical deflection on ballasted railway tracks from a set of cases of railway track typologies which differ in six track parameters: embankment height, ballast thickness, sleeper spacing, rail pad stiffness, Young??s modulus of the embankment material and the load applied to the structure. Finite element method has been the tool to assess the structural combinations and the results provided by linear and nonlinear analyses have been contrasted. Then, a new formulation for the deflection estimation in terms of the aforementioned parameters is presented based on a multiple regression model. The results provided by this formulation have been compared to those obtained from the classic Zimmermann theory. Finally, a stress analysis has been performed to complete the study and better understand the global behaviour of the railway structure. This article pretends to improve the design process and construction of ballasted railway tracks by means of proposing a formulation which estimates the track deflection to obtain the optimum track stiffness.     

铁路轴承振动质量对可靠性的影响

通过对内滚道几何精度引起的轴承振动进行评估,理论上分析这些振动加速度对铁路轴承可靠性的影响趋势,承振动质量验收提供依据。得出这些几何精度所能产生的振动加速度,并从为铁路轴承生产过程中的质量控制及成品铁路轴     

铁路提速客车轴承磨加工工艺研究

针对铁路提速客车轴承的特殊性．将原有的磨加工工艺进行了改进，从而提高了产品的使用性能和使用寿命，满足成品设计的要求。     

钢轨轮廓测量中的车体振动补偿问题研究

采用车载方式进行钢轨轮廓高精度测量,必须进行车体振动补偿.针对车体振动对钢轨轮廓测量带来的误差影响,提出将车体振动分解为同一平面内的平移振动分量和旋转振动分量,对左右股钢轨轮廓数据各个振动分量分别进行补偿.研究了用于钢轨轮廓测量的激光摄像式传感器标定计算方法、车体振动补偿计算方法.给出了基于激光摄像技术的钢轨轮廓测量方案.针对现场钢轨轮廓测量数据检测精度难验证的问题,建议采用钢轨磨耗测量数据验证.研制了基于激光摄像技术和车体振动补偿技术的钢轨轮廓检测装置.每隔100 m共选取10个采样点,分别在人工静态、振动补偿前动态、振动补偿后动态测量钢轨磨耗数据,以静态测量数据为基准,验证振动补偿有效性.结果表明,采用车体振动补偿后,左右股钢轨磨耗测量误差标准差各自减小2.0 mm,测量误差百分比各自减小38.8％、39.7％.选取200 m长线路分别以10 km/h、40 km/h、80 km/h进行钢轨轮廓动态测试,以10 km/h测量数据为基准,验证钢轨磨耗测量数据一致性.结果表明,动态测量钢轨磨耗数据重复性误差均方差控制在0.40 mm以内.     

An optimized method to evaluate the performance of trench isolation for railway-induced vibration

A variety of technologies are employed to reduce ground borne vibrations near railway lines. In this paper, the performances of different signal-processing algorithms are discussed in an effort to define an optimized methodological approach for evaluating the reduction potential of mitigation techniques. Different post-processing analysis methods have been applied to acceleration data collected during the passage of a train in order to evaluate the performance of a trench realized to improve the quality of life near railway lines. RMS computation at steady-state and amplitude of frequencies in the averaged spectra were used as a first assessment procedure, while joint time–frequency analysis were used for the characterization of the signals during transients. The possibilities provided by wavelet techniques were then investigated and compared with those of the classical Fourier analysis. Experimental results show that the wavelet approach can be used both to evaluate the effectiveness of the mitigation techniques, and to analyze the structure of the acceleration signals generated by trains.     

高速铁路轴承磨削规范的制定

针对高速铁路轴承采用不同材料及其形状、尺寸和各磨削工序使用的磨加工设备等特性,制定了高速铁路轴承磨削规范,对选择磨具、砂轮转速、工件转速、进给量及光磨时间等磨削参数提出了明确规定,为生产出高精度和高质量产品提供了技术保障。     

Effect of under-platform dampers on the forced vibration of high-speed rotating blades

Journal of Mechanical Science and Technology - Under-platform dampers (UPDs) are commonly used to adapt turbine blade vibration characteristics by friction. However, acquiring their effect on the...     

高速列车横向悬挂系统振动结构研究

研究了高速列车横向悬挂系统的振动结构。为了抑制列车横向振动,提高平稳性,分析了列车横向悬挂系统振动结构的主要矛盾和相互关系。采用Simulink仿真软件建立了17个自由度的列车横向悬挂系统车体模型,以加速度功率谱密度函数为依据,建立了关系函数,对横移、侧滚、摇头振动和前、后端转向架横向合成振动指标相互关系进行了分析。结果表明,列车在高速情况下,在最令人敏感的低频段,摇头振动是引起列车横向振动的主要因素;随着速度的提高,主要影响因素从摇头振动向横移和侧滚振动发生着量的变化。     

基于Simulink仿真模拟车辆垂向振动

根据Matlab/Smulink建立客车两种垂向振动模型：具有动力吸振系统以及具有半主动控制系统,分4种状态：时速分别为100km/h、200km/h时,短波激励波长10m,长波激励波长50m,用变步长四阶龙格—库塔法进行仿真。在时域内对比仿真结果,得出阻尼开关的半主动控制在隔振方面优于动力吸振器。     

Numerical investigation on the effects of real industrial bleeding geometry in a high-speed compressor stage

A bleeding system is necessary for gas turbines and may largely affect the compressor performance. In the existing literature the circumferentially uniform bleeding is widely studied; however, it is different from the industrial bleeding geometry and may not fully reflect the effects on the compressor. We conducted a numerical study to investigate the flow mechanism of the real industrial bleeding geometry in a single-stage high-speed axial compressor environment. Results show that bleeding effects increase the adiabatic efficiency and slightly reduce the total-to-static pressure ratio. Furthermore, it is discovered that a locally aperiodic flow field in the rotor passages is generated due to the real bleeding geometry. In the tip region the maximum incident angle difference can reach 1 degree. Locally aperiodic bleeding makes the tip leakage strength and blockage different in various rotor passages.

     

Extracting modal parameters of high-speed railway bridge using the TDD technique

In case the excitation frequency induced by a high-speed train passage coincides with the natural frequency of a railway bridge, a resonance of the bridge occurs. In addition, if the train is passing through the bridge very quickly, measurable time samples can be of limited numbers and thus modal parameters of the bridge can hardly be obtained. To get over this, effective technique for the extraction of modal parameters is proposed in the present study. With the cross correlations among free vibration responses immediately after the train passes, mode shapes are obtained by TDD (time domain decomposition) technique while temporal modal parameters are extracted by the proposed sensitivity-updating system identification technique. A two-span steel composite girder bridge, which is of typical Korean high-speed railway bridge system, is employed to verify the proposed approach. Comparative studies reveal that the predictions of the proposed approach agree well with those by the well-known existing methods. It is thus postulated that the present approach is promising in terms of both accuracy and applicability.     

铁路提速客车轴承的台架运转性能试验分析

通过台架试验的温升对比数据分析和分解检查,验证了铁路提速客车轴承设计的正确性,可完全满足我国铁路提速客车运用的需要,可以为装车试验做充分的准备。     

高速电机轴承振动检测仪的研制

针对3 000~6 000 r/min的深沟球轴承的检测技术要求,研发了一种高转速的轴承振动检测仪,填补了业内高速电机轴承振动检测技术的空白,为高速电机轴承的成功生产提供了强有力的动态性能检测保障。     

A novel experimental research on vibration characteristics of the running high-speed motorized spindles

Because of the complicated running condition and many unpredicted factors such as unmodelled dynamics and external disturbances, the fault analysis of the high-speed motorized spindle is proved difficult. In this paper, a novel experimental method is proposed to research the vibration characteristics of the running high-speed motorized spindle. The method consists of four steps. Firstly, the vibration signal measurement and processing system are built according to data collector and signal analysis software, and then, the vibration signal of the spindle extracted from sophisticated experimental environment is studied by using harmonic wavelet transform for its advantages, such as ultra-narrow band, high resolution detection and ability of extracting weak signal. After that, local frequency domain zooming technique of harmonic wavelet packet is employed to study the vibration spectrum of the spindle at eight different rotating speeds. Furthermore, the axis orbit of the rotor is purified successfully, which can serve as verification basis for subsequent on-site fault diagnosis. Finally, a comparative analysis of eight different vibration signals under the same load but different speeds condition is carried out, the spectral components are classified into two types: the repeated ones and the regular ones. The accordance between experimental results and theoretical analysis suggests that the proposed method in this paper is effective.     

600t高速铁路箱梁架桥机的三维有限元分析

应用国际上广泛使用的大型通用有限元分析程序Super SAP对600 t高速铁路箱梁架桥机JQ600进行了整体和局部应力计算及稳定性分析,其中关键部位的局部应力计算结果与实测结果接近.说明本文所使用的方法和技巧是有效的.这对开发更大吨位的高速铁路架桥机的力学计算有一定的指导意义.     

The thermo-mechanical behavior of brake discs for high-speed railway vehicles

Journal of Mechanical Science and Technology - The structure of a brake disc is coupled to the axle and rotates together with the wheel. A brake disc is a friction-type device that presses the pad...     

基于多智能体的斜拉索分布式智能减振控制系统

目前磁流变减振器已越来越多地被应用于斜拉桥拉索减振,但是这种减振器装置在主、被动工作模式间还缺乏有效的自动转换机制,往往需要人工切换。为了解决该装置在灵活性、自主性和自适应性等方面的不足,本文在斜拉索减振控制系统中引入多智能体技术,提出了基于多智能体技术的斜拉索分布式智能减振控制系统的结构模型和功能,该模型将传统控制系统的功能划分入不同的智能体层,分析了系统的体系结构和工作原理,研究了其实现方式,并将系统应用于洞庭湖大桥上。应用结果表明,该系统在原有装置基础上具有了较高的智能性,表现出更快的反应性和更好的自适应性。