共查询到20条相似文献，搜索用时 31 毫秒
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In this study a new dynamic model of a rotor system is established based on the Hamilton principle and the finite element method (FEM). We analyze the dynamic behavior of the rotor system with the coupled effects of the nonlinear oil film force, the nonlinear seal force, and the mass eccentricity of the disk. The equations of the motion are solved effectively using the fourth order Runge-Kutta method in MATLAB. The dynamic behavior of the system is illustrated by bifurcation diagrams, largest Lyapunov exponents, phase trajectory diagrams, and Poincaré maps. The numerical results show that the rotational speed of the rotor, the pressure drop in the seal, the seal length, the seal clearance, and the mass eccentricity of the disk are the key parameters that significantly affect the dynamic characteristics of the rotor system. The motion of the rotor system exhibits complex types of periodic, quasi-periodic, double-periodic, multi-periodic, and chaotic vibrations. This analysis can be used to guide the design of seal parameters and to diagnose the vibration of rotor/bearing/seal systems. 相似文献
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发动机涡轮增压器是一种轻型高速旋转机械,其作用是通过增压增加气缸进气量,提高发动机的燃油经济性和动力性．发动机涡轮增压器核心部件是双盘双支撑的转子轴承系统,所以对转子轴承系统运动稳定性的研究显得尤为重要．通过传递矩阵法建立求解涡轮增压器转子系统临界转速的计算模型,将某型国产汽油机涡轮增压器转子系统的参数带入数学计算模型．利用Matlab软件编程计算涡轮增压器转子系统的临界转速,并通过台架试验验证了理论计算的正确性,为涡轮增压器转子系统设计提供理论参考． 相似文献
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Wei LI De-ren SHENG Jian-hong CHEN Yong-qiang CHE 《浙江大学学报(A卷英文版)》2014,15(11):883-895
研究目的：研究双盘双跨转子/轴承/汽封系统在非线性油膜力和非线性汽封力共同作用下的动力学特性,分析了转子转速、密封力、油膜力和联轴器刚度等因素对转子稳定性的影响。创新要点：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型,使得双跨多节点的转子系统数值求解更加容易。研究分析转子转速、非线性密封力、非线性油膜力和联轴器刚度等因素对转子稳定性的影响,为大型转子系统的设计提供理论基础。研究方法：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型（图1和2）。应用四阶Runge-Kutta法进行数值求解,并采用轴承处、圆盘处的分岔图、时程图、庞加莱映射图、频率图和相轨迹图等来分析转子系统的动态特性。重要结论：1.通过数值计算分析,转子的转速、非线性汽封力、非线性油膜力和联轴器的刚度对双跨转子的稳定性有重要的影响作用。2.随着转速的上升,双跨转子系统从最初的稳定运动,到三倍周期运动,到准周期运动和多倍周期运动交替出现,运动特性相比单跨转子系统要更为复杂。 相似文献
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为了解不同空调风机的内流机制,采用数值分析和PIV实验研究相结合的方法对空调用贯流风机和轴流风机内部复杂的旋涡流动现象进行了研究。结果表明:空调壁挂机用贯流风机内部偏心涡沿轴向具有明显的三维分布特性,偏心涡径向位置沿轴向几乎没有变化,其周向位置沿轴向不断改变。贯流风机偏心涡卷吸区域随负载提高而增强。高负载时,偏心涡更加靠近叶轮中心和蜗壳方向。空调室外机用开式斜流风轮的叶尖涡产生于距叶片前缘1/4区域,靠近吸力面。叶尖涡随风轮转速的提高而增强,并沿着与风轮旋向相反的方向朝下游发展。 相似文献
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An online experiment to acquire the interior noise of a China Railways High-speed (CRH) train showed that it was mainly composed of middle-low frequency components and could not be described properly by linear or A-weighted sound pressure level (SPL). Thus, the appropriate way to evaluate the high-speed train interior noise is to use sound quality parameters, and the most important is loudness. To overcome the disadvantages of the existing loudness algorithms, a novel signal-adaptive Moore loudness algorithm (AMLA) based on the equivalent rectangular bandwidth (ERB) spectrum was introduced. The validation reveals that AMLA can obtain higher accuracy and efficiency, and the simulated dark red noise conforms best to the high-speed train interior noise by loudness and auditory assessment. The main loudness component of the interior noise is below 27.6 ERB rate (erbr), and the sound quality of the interior noise is relatively stable between 300–350 km/h. The specific loudness components among 12–15 erbr stay invariable throughout the acceleration or deceleration process while components among 20–27 erbr are evidently speed related. The unusual random noise is effectively identified, which indicates that AMLA is an appropriate method for sound quality assessment of the high-speed train under both steady and transient conditions. 相似文献
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With the development of high-speed train, it is considerably concerned about the aerodynamic characteristics and operation
safety issues of the high-speed train under extreme weather conditions. The aerodynamic performance of a high-speed train
under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper. The impact
of heavy rainfall on train aerodynamics is investigated, coupling heavy rain and a strong crosswind. Results show that the
lift force, side force, and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall
rate of 60 mm/h. when considering the rain and wind conditions. The increases of the lift force, side force, and rolling moment
may deteriorate the train operating safety and cause the train to overturn. A quasi-static stability analysis based on the
moment balance is used to determine the limit safety speed of a train under different rain and wind levels. The results can
provide a frame of reference for the train safe operation under strong rain and crosswind conditions. 相似文献
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研究目的：求斛双圆盘转了-密封系统的非线性振动特性和运动响应 创新要点：采用有限元法（FEM）和拉格朗目方程求解双圆盘转子-密封系统,进而为研究多级转了系统的非线性振动问题提供有效方法。研究方法：基于有限元法（FEM）和拉格朗目方程。同时利用四阶龙格-库塔法求解系统动特性运动响应情况,利用风岔图、时间历程图、轴心轨迹图、庞加莱映射和幅值谱等分析图研究双圆盘转子-密封系统的非线性振动特性。重要结论：随着转速的增大,双圆盘转子-密封系统呈现丰富的非线性运动形式,包括周期性运动、多周期运动,准周期运动以及混沌运动。在右端圆盘不平衡质量小于34kg、密封间隙范围为0.376mm-0.54mm、密封长度大于0.13m或者密封压差高于0.104MPa的情况下均有利于提高双圆盘转子-密封系统的稳定性。 相似文献
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数控高速切削加工与普通数控加工不同,具有其独特的性质,所以对刀具路径的规划也有着更高的要求,主要为以下几点：保持最大和稳定的切削速度;避免不连续和突然的加速度变化;刀具运动保持恒定的进给速度,产生相同体积的切屑;在保持插值公差的前提下,尽可能减少程序段数：提供高度连续的光滑的刀位数据。所以刀具路径规划主要是对铣削方向、进退刀方式、移刀方式、走刀方式、拐角处理等方面进行研究。本文仅以UG NX3．0为例对数控高速切削加工的刀具路径进行研究。 相似文献
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郭建民 《张家口职业技术学院学报》2002,15(4):50-52
将DCP90凸齿脱胚磨的动盘与前轴承距离缩短，机壳与轴承盒端盖由填料密封改为迷宫式密封，在机壳内用厚度为2mm不锈钢板衬里，可以提高设备效率，改善设备条件，节约维费用和时间。 相似文献
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拜读某高等数学教材中发现了答非所问的速度改变问题,该教材某例题把速率改变的结果当成了速度改变的结果,因此有必要澄清加速与减速是对速率改变而言,而速度单增与速度单减是对速度改变而言。借助函数单调性判定定理,澄清用的符号判定速度改变（速度单增（或速度单减））,而非判定速率改变（加速（或减速））,完善该实例。本文进一步解决了如何用构造的符号判定速率改变的问题。有意思的是加速与减速,可能是速度单增,也可能是速度单减,体味数学中关于正（或负）号美。 相似文献
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A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h. 相似文献
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高速铁路站台安全门对乘客的安全性和舒适性起到了很大的作用,但如何合理设置安全门的高度及位置,目前国内尚无相关的理论支持和原始数据的积累.针对以上问题,通过实测高速列车以2种不同的速度通过站台时的风速(影响乘客候车的安全性)和噪声值(影响乘客乘坐舒适性),并将测试数据与相关标准进行对比,提出了安全门的高度应当高于人耳的高度即高于1.5m,对高速列车站台的安全性和舒适性都有较大的改善,为今后高速铁路站台安全门设计提供了参考. 相似文献
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高速铁道车辆风致安全性研究 总被引：1，自引：0，他引：1
Xin-biao XIAO Liang LING Jia-yang XIONG Li ZHOU Xue-song JIN 《浙江大学学报(A卷英文版)》2014,15(9):694-710
研究目的：随着世界高速铁路网的不断扩张,高速列车的风致安全性成为高速铁路系统中的关键科学问题之一。本文利用车辆-轨道耦合动力学理论分析方法,确定强横风作用下高速铁道车辆的安全运行区域,为强风地带高速列车的安全控制提供依据。创新要点：首次提出了考虑多种影响因素和脱轨评价指标的高速列车脱轨安全域分析方法,并运用到了高速铁道车辆风致安全性研究中。研究方法：基于车辆-轨道耦合动态响应及多种安全性评价指标得到横风作用下高速铁道车辆的安全运行区域和脱轨区域。重要结论：铁道车辆安全性评价指标中,轮重减载率对横风激励最为敏感,其确定了强风作用下高速车辆安全运行区域的边界。 相似文献
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闫银超 《新疆职业大学学报》2008,16(3):19-20
本文着重探讨了《冈底斯的诱惑》突破传统的叙事技巧,应用消解真实、营造迷宫、插入评论等叙事手法,使传统单向、封闭的叙事结构不断走向多元、开放,为叙事文学开拓出了一条新路。 相似文献
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运用新微积分理论(见文献[1])，定义了瞬时线速率、瞬时线速度、瞬时平面角速率、瞬时平面角速度、瞬时线加速度、瞬时角加速度．并阐明了它们之问的关系． 相似文献
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张潮 《河北能源职业技术学院学报》2014,14(3):59-61
鉴于煤矿目前的矿井提升机普遍使用交流绕线式电机转子串电阻调速,提升机在减速和爬行阶段,负载变化时,实现恒减速难度大,经常会造成过放或过卷,转子串电阻能耗大,电路复杂。针对上述问题,设计了西门子变频器在提升机调速系统中的应用。解决了提升机恒加速和恒减速控制,避免了过卷和过放,控制电路简单,具有十分广阔的适用性。 相似文献
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王云峰 《湖南大众传媒职业技术学院学报》2008,8(6):22-28
电视湘军的崛起是改革开放的产物。十一届三中全会以来,特别是1993年以来,电视湘军的发展之路,就是改革之路。历经三轮改革,电视湘军已经步入集团化、品牌化的高速发展阶段,引起业界和学界的广泛关注。电视湘军改革的思路与实践,为中国电视发展提供了一个成功范本。 相似文献