磁悬浮转子轴向位置精度的实验研究

以实际涡轮膨胀机为对象 ,通过不同轴向传感器测量方式下实验结果的比较 ,研究了轴向控制电流、轴向工作载荷、变化的温度及磁场、转子及推力轴承的热膨胀等因素与转子轴向位置精度的关系。提出了一种用于实际涡轮膨胀机的具有冗余结构的三传感器测量方式 ,解决了转子轴向漂移问题。本文的分析方法也可用于转子径向位置精度的分析以及磁悬浮轴承转子系统的实时工况监测。     

高速永磁电机转子轴向碰磨故障的试验研究

随着旋转机械转速及效率的提高,设备部件间轴向间隙越来越小,发生轴向碰磨的可能性大大增加,而目前针对轴向碰磨的试验研究较少。为研究高速永磁电机转子的轴向碰磨故障,建立四磁盘气体轴承-转子系统实验台,该试验台采用纯静压气体轴承支承,轴承两侧分别布置两个相同大小的磁盘。在实验台上进行转子振动试验,以研究转子的轴向碰磨特性。结果表明:高速永磁电机转子发生轴向碰磨会导致出现变化趋势相反的双低频现象,且碰磨的严重程度会影响低频的重复性。采用ANSYS对磁盘进行应力变形分析,表明发生轴向碰磨的原因是设备的轴向间隙较小,且高转速下磁盘受到较高的集中应力从而造成磁盘的轴向变形,引起了轴向碰磨的发生。     

轴封型核主泵轴向力计算方法及标定研究

轴封型核主泵是核电站一回路系统中唯一的旋转设备,属于高温、高压、受核辐照的压力边界一级设备。由于系统压力大,转子系统所承受的轴向载荷也大,轴向载荷能否精确确定影响转子各个零部件的设计分析和设计开发,油润滑推力轴承提供很重要的设计技术参数。本文通过举例,根据核主泵在电站系统中运行期间的载荷变化,计算核主泵转子轴向力,并在水力模型装置上设置力传感器,验证计算方法的正确性。     

带缓冲垫圈的辅助轴承结构特性研究及应用仿真分析

辅助轴承主要用于承载高速跌落的转子,并在承受巨大冲击载荷时不会失效。为降低跌落时对辅助轴承的碰撞力,保护电磁轴承及转子系统,提出一种基于轴向缓冲垫圈的辅助轴承结构。结合清华大学核研院的10 MW高温气冷堆电磁轴承氦风机实验台架,基于有限元方法,对转子跌落时辅助轴承外圈添加和未加轴向缓冲垫圈时辅助轴承的结构特性以及受力情况进行仿真分析,得到碰撞力最大时刻结构的应力分布,从理论上验证了辅助轴承在跌落时的可靠性。结果表明：缓冲垫圈的加入可有效减小转子跌落对辅助轴承的碰撞力,对辅助轴承起到了一定的保护作用,为进行转子跌落实验及该结构的实际应用提供了重要参考。     

控制力矩陀螺转子1阶临界转速及轴向振动响应分析

基于转子动力学及谐响应理论,建立了高速转子的有限元分析模型,研究了旋转质量本体辐板倾斜角、轴承预紧力、轴承安装跨距对高速转子1阶临界转速及轴向振动响应的影响。结果表明:转子1阶临界转速随轴承预紧力的增加而增大,随轴承安装跨距的增加而减小,随旋转质量本体辐板倾斜角的增加呈先增大后减小的趋势;高速转子的放大因子随辐板倾斜角和轴承预紧力的增加而增大;轮缘的轴向振动位移响应随轴承预紧力的增加而减小,随辐板倾斜角的增加呈先减小后增大的趋势;轴承安装跨距对高速转子的放大因子和轮缘的轴向振动位移响应的影响较小。     

带缓冲垫圈的辅助轴承结构特性研究及仿真分析

辅助轴承主要用于承载高速跌落的转子,并在承受巨大冲击载荷时不会失效。为降低跌落时对辅助轴承的碰撞力,保护电磁轴承及转子系统,提出一种基于轴向缓冲垫圈的辅助轴承结构。结合清华大学核研院的10 MW高温气冷堆电磁轴承氦风机实验台架,基于有限元方法,对转子跌落时辅助轴承外圈添加和未加轴向缓冲垫圈时辅助轴承的结构特性以及受力情况进行仿真分析,得到碰撞力最大时刻结构的应力分布,从理论上验证了辅助轴承在跌落时的可靠性。结果表明:缓冲垫圈的加入可有效减小转子跌落对辅助轴承的碰撞力,对辅助轴承起到了一定的保护作用,为进行转子跌落实验及该结构的实际应用提供了重要参考。     

离心式氮压机止推轴承的失效分析与防治

前言大型、高速离心式压缩机和蒸汽透平机普遍采用多瓦块活动式止推轴承,用以承受转子上残余轴向推力,限定转子轴向位置,吸收转子轴向振动能量。如果止推轴承因磨损、腐蚀或烧熔而失效,转子将发生轴向窜动,破坏迷     

BSG轴承用高温高速高载荷试验机的开发与应用

以自主开发BSG轴承用高温高速高载荷试验机为目的展开了以下研究:进行试验机机械结构的整体设计;设计开发轴向和径向加载装置,真实模拟轴承实际运转过程中承受的载荷;设计开发基于PID控制的加热装置,可以准确控制测试环境的温度;设计试验机的控制系统及软件系统;制造出BSG轴承用高温高速高载荷试验机样机,完成设备调试、系统运行与改进;利用该设备进行轴承的寿命试验。通过对试验数据分析表明,试验机结构设计合理,性能可靠。     

五自由度全永磁轴承系统的稳定悬浮特性分析

为探讨永磁悬浮轴承系统的稳定悬浮特性,从轴承刚度角度对五自由度全永磁轴承系统的稳定悬浮特性进行了分析。采用等效磁荷理论建立永磁轴承的承载力、承载力矩和刚度的数学表达式,并利用蒙特卡洛法对表达式中存在的四重积分进行求解。探究转子在受迫进动情况下以及受到外力矩干扰时继续保持稳定旋转所需要的最低临界转速。基于轴向永磁轴承与径向永磁轴承的结构,提出一种六磁环五自由度全永磁轴承系统结构模型,对全永磁轴承的转子系统承受轴向和径向外载荷的承载力、力矩和承载刚度进行分析,得出轴向可以承受外载荷而径向无法承受外载荷,即静态下轴向可以稳定悬浮、径向不能稳定悬浮,符合Earnshaw定理。利用刚性转子的陀螺惯性力矩来承受全永磁轴承系统的不平衡力矩和外力矩,从而保持转子定轴自稳定悬浮,并对系统稳定悬浮特性进行计算,结果表明转子在超过最低临界转速后是可以实现动态稳定悬浮的,具有一定的工程应用价值。     

涡轮增压器起停过程转子轴向力测试研究

涡轮增压器起动和停机过程转子所受的轴向力大小对于增压器的设计是至关重要的。以JP60C型涡轮增压器为研究对象,利用有限元方法计算增压器止推轴承的应变场,确定了转子轴向力的测量方案。并在增压器性能试验台上对增压器转子轴向力进行实验测量。实验结果表明,增压器起动和停机时,止推轴承所承受的轴向力远大于稳定工作时所承受的轴向力;且起动和停机工况下,转子所受的轴向力方向相反。试验结果将为增压器止推轴承的合理设计提供理论依据。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.