New cylinder liner surfaces for low oil consumption

Anticipated emission legislation and reduced fuel consumption are the main driving forces when developing new engines. Optimization of the active surfaces in the piston system is one possible way to meet the above demands. In this study the effects of surface topography and texture direction of the ring/liner contact on oil film thickness and friction were simulated and experimentally tested. “Low wear” results from the experimental wear tests with “glide honed” smooth liner surfaces supported the “low friction” simulation results. In addition a new wear volume sensitive surface roughness parameter, R_ktot, based on the Abbot–Firestone bearing area curve was introduced.     

储能飞轮转子的研究现状与进展

储能飞轮系统是高效、环保的新型能源技术,广泛应用于电动汽车、通信、风力发电、智能电网、航空航天等工程领域,是具有发展前景的能源技术.文中综述了储能飞轮系统在工程中的应用,介绍了飞轮转子在材料选择、转子形状以及加工制造工艺等方面的发展.     

Collision between a ring and a beam

With car–parapet collision accidents in mind, a normal collision between a free-flying half ring and a simply supported beam with/without axial constraints is studied, in which an elastic–plastic half ring with an attached mass and the elastic–plastic beam are taken as the simplest models of a car and a parapet, respectively. Particular attention is paid to the energy partitioning between the two structures and the evolution of the contact regions during collision. A mass–spring finite difference (MS–FD) model is employed whilst the large deflection and axial stretching/compression are incorporated. The numerical results show that the less stiff (i.e. softer) structure will dissipate more energy and the contact regions will move away from the initial contact points. With the increase of the relative thickness of the beam to the ring, the final deformation of the half ring will transform from a “U” shape to a “W” shape.     

Modeling and verification of a five-axis laser scanning system

Today several new kinds of laser beam sensors appear with high resolution and accuracy and find their applications in reverse engineering and quality control. Due to the incapability of changing their orientations continuously in response to the surface fluctuation of a part to be measured, they are not competent for measuring parts with complicated structures. In this paper a five-axis laser scanning system integrated with a CMM, a laser beam sensor and a PH10 rotary head is proposed, which can measure complicated parts by frequently indexing the laser sensor approximately consistent with the normal direction of the surface. As the laser value is a 1-D data and the measured data must be given in 3-D expression in the world coordinate system, a system model for coordinate transformation is established. An “equivalent probe” approach is presented for system verification, and an iterative verifying process is adopted to eliminate the verification error caused by the inclination error of the laser sensor. Experiment study shows that the system can measure a part from any direction with an accuracy of 30 μm.     

Kinematics of motions in rotor system during contact between rotor and floating elements

The contact regimes in the rotor system when the contact of the rotor with light movable elements of the system have been considered The vibrations of an imbalanced rotor–floating ring system when rotating the rotor inside the floating ring when permanent contact with them have been investigated. Furthermore, the ring vibrations occur, during of which it runs the rotor when permanent contact with it in the direct precession regime (the precession direction coincides with the rotation direction) (hula hoop-type vibration). This article considers the kinematics of ring motion. The trajectories of ring motion in both absolute and relative motion at different ratios between the radii of the ring and rotor have been plotted. It has been revealed that the ring vibrations are a direct asynchronous precession; furthermore, the ring points circumscribe epitrochoids and the trajectory shape depends significantly on the ratio between the radii of the rotor and the ring.     

复合材料储能飞轮转子的设计

当转子的最大环向应力和最大径向应力同时达到它们各自方向上的强度时,可以得到最优内外径比.基于该设计理念对影响飞轮储能密度的复合材料轮缘内外径比λ进行设计,并选用各向异性材料碳纤维环氧树脂复合材料、玻璃纤维环氧树脂复合材料及各向同性材料高强铝合金为飞轮转子材料进行最大边缘线速度及最大单位质量储能的比较,结果表明:碳纤维环氧树脂复合材料所设计的飞轮转子单位质量储能最高,体积最小,边缘线速度最大.     

液压储能技术的研究现状及展望

由于节能减排的需要,液压系统中的能量损耗成为研究热点,采取合适的方式对液压能进行储存至关重要。通过总结液压系统中常见的储能方式,引出对以蓄能器为储能元件的液压式储能技术的详细介绍,梳理了液压储能技术的发展及改进情况,提出了未来的研究方向,为相关行业技术人员了解国内外液压储能技术的研究现状及研发新的液压储能技术提供参考。     

Method of movable lattice particles

A new simulation technique for modeling elastoplastic deformation and friction processes based on the dynamics of a system of “lattice particles” is proposed. In usual simulation methods like molecular dynamics, only interactions compatible to the symmetries of space (invariant with respect to translations and rotations) are used. In the proposed method, the interaction potentials depend both on the relative position of particles and the orientation of their relative radius vector with respect to prescribed “lattice directions”. We show that in spite of this relation with the “external space”, the system behaves, in linear approximation, as an isotropic elastic medium invariant to both the translations and rotations of the medium as a whole. The coupling with the external space occurs to be a surface effect, which either does not play an important role (if the motions of the boundaries are prescribed) or can be handled properly by introducing fictive compensating surface forces. Introduction of forces depending on the orientation of the local surroundings of a particle makes it possible to describe elastic media with arbitrary elastic properties by using only interactions between the next neighbours. The system of lattice particles shows better stability properties and allows one to describe large plastic deformations, avoiding problems of “packaging” typical for many particle methods.     

电涡流传感器检测磁悬浮转子轴向位移的方法

磁悬浮转子的轴向位移常常利用电涡流传感器从转子轴向方向来检测,这一方法具有一定局限性。针对这一情况,在分析了电涡流传感器的工作原理以及输出特性的影响因素后,研究了利用被测导体的台阶表面来检测导体沿传感器径向方向的位移的方法。在该方法中,采用与差动相反的思想,将关于被测导体对称布置的两个传感器的输出进行加和,来消除传感器线圈与导体间距离的变化对检测结果的影响。结合磁悬浮转子的特性,提出了磁悬浮转子轴向位移径向检测的方法,并进行了实验验证,结果表明传感器的输出电压之和与转子轴向位移之间具有良好的线性关系和灵敏度,验证了该方法的正确性和可行性。     

飞轮储能系统推力盘布局优化分析

基于600 Wh飞轮储能系统对现有结构进行结构布局优化,提出了2种针对推力盘安装位置不同的飞轮储能系统的结构布局,利用ANSYS Workbench对3种结构进行结构力学分析。结果表明:吊装式结构的飞轮储能系统力学性能最差,嵌式结构的飞轮储能系统力学性能最好,夹式结构介于两者之间。这为今后的飞轮转子系统结构设计提供了参考与指导。     

Optimum design of multi-ring composite flywheel rotor using a modified generalized plane strain assumption

A numerical method for calculating the stress and strength ratio distribution of the hybrid rim-type composite flywheel rotor is presented with a consideration of the thermally induced residual stresses. The axisymmetric rotor is divided into several rings and the stiffness matrix for each ring is derived by solving the radial equilibrium equation and the stress–strain–temperature relations. The ring stiffness matrices are assembled into a symmetric global matrix satisfying the continuity equations at each interface with the assumptions of a modified generalized plane strain (MGPS). In the MGPS, the z-directional axial strains are assumed to vary linearly along the radial direction; ε_z=ε₀+ε₁r. The conditions that the z-directional force and the circumferential moment resultants vanish are thus used to solve the z-directional axial strains as well as the radial and circumferential strains. After solving the strain distributions, the on-axis stresses and the strength ratios are calculated at each ring. Three-dimensional finite element method (3D FEM) is then used to verify the accuracy of the present method. The results are also compared with those based on the assumption of a plane stress (PSS). In this case, the analysis of MGPS better matches with 3D FEM results than PSS. An optimum design is then performed maximizing total stored energy (TSE) with the thickness of each composite rim as design variables. The optimal design obtained in this study, which considers material sequence, provides a more effective way of maximizing TSE. It is found that the consideration of the residual stress in the design of the hybrid flywheel rotor is crucial. The result of the optimal designs shows that TSE with consideration of ΔT reduces by about 30%.     

带弹性环保护轴承的动力学特性

提出在传统保护轴承外圈加弹性环来提高其在主动磁悬浮轴承(Active magnetic bearing,AMB)系统中的工作性能。为完善转子跌落仿真模型,得到AMB失效前转子准确的运动状态,理论推导得到AMB的支撑动刚度曲线,进而基于有限元分析方法得到转子在其支撑下的模态,并与试验结果进行对比,验证所得刚度曲线的正确性。在刚性转子理论基础上,建立转子在AMB系统中的动力学模型。基于Hertz接触理论,分别建立AMB失效后转子与保护轴承内圈之间的碰撞模型和保护轴承的实时动刚度模型。根据所建立的模型,对不同弹性环支撑刚度阻尼在不同初始转速下跌落后的动力学响应进行仿真计算,并与无弹性环状态下跌落结果进行对比。仿真分析结果表明,选用合适的弹性环有利于降低转子跌落后的振动幅值和碰撞力。分别在不同初始状态下进行跌落试验研究,试验结果与理论分析结果基本相符。     

电力储存用飞轮系统的控制模型研究

对用于电力储存的 10MWh级飞轮系统的控制模型进行了研究 ,主要介绍了对大容量飞轮储能系统的构造设计、振动分析、没有考虑系统陀螺效应的有限元模型、考虑陀螺效应的有限元模型以及考虑陀螺效应的弹性支持的回转轴模型     

弹性蓄能密封圈结构优化设计及验证

以OmniSeal 103A系列弹性蓄能密封圈为参考,提出密封夹套和与密封沟槽配合尺寸设计方法,并对弹性蓄能密封圈的结构进行优化,设计外唇面带有15°斜面的弹性蓄能密封圈JT1和外唇面为圆弧面的弹性蓄能密封圈JT2。设计实验从正反向摩擦力和密封性2个方面对两款弹性蓄能密封圈进行性能验证,并且与OmniSeal 103A系列中同规格密封圈性能进行对比。结果表明：JT1蓄能密封圈很大程度上提升了密封性能并且其抗摩擦性能也没有大幅下降,而JT2蓄能密封圈提升了抗摩擦性能,且密封性基本与OmniSeal蓄能密封圈相当。因此,JT1蓄能密封圈更适用于对密封性要求更高的场合,JT2蓄能密封圈更适用于对抗摩擦性要求更高的场合。     

集中式储能电站接入下的区域电网自动电压控制

研究和开发了一种集中式储能电站接入下的区域电网自动电压控制系统,提出一种集中式储能电站接入下按市调AVC、地调AVC、储能电站AVC子站三级分层控制架构,并阐述三级分层控制关键技术和控制策略。在某座大型集中式储能电站进行试点应用,为今后规模化集中式储能系统在电网侧的多元化应用,提供有效的控制理论和技术支撑。     

电磁轴承-刚性转子系统轴承传递力主动控制

针对电磁轴承支承的刚性转子系统轴承传递力的主动控制,分析了轴承传递力的组成,基于一种变步长三角形迭代搜寻算法辨识出转子位移中同频分量的方法构建了零电流控制及零传递力控制策略,分别在恒定转速和匀加速运动过程中对两种控制策略的有效性进行了仿真分析,最后在某磁悬浮高速飞轮储能系统上进行了试验验证。理论与试验结果表明,零电流控制策略能对绝大部分轴承传递力进行抑制,零传递力控制策略能对轴承传递力进行完全消除。     

小型风力-压缩空气储能系统研究概述

小型压缩空气储能系统是分布式能源系统的重要组成部分，是弥补新能源发电系统波动性和随机性的一种有效方法。通过查找国内外相关文献，对小型压缩空气储能系统的关键部件进行综述，得到小型压缩空气储能技术和释能技术的发展方向。基于当前研究现状，得出结论：首先为了提高系统效率要解决耦合后功率不匹配问题，其次为满足风力发电机组空间受限的特点应对压缩空气进行一体化设计，最后对压缩空气关键技术进行总结，并给出了有待解决问题的研究方案。     

Detachment of an elastic beam from a viscoelastic support: A variational approach

The paper is devoted to the analysis of failure in multi-layer composite materials. For the experimental study of the failure mechanism, the peel tests are used. The peel test is modeled as the detachment of an elastic beam attached to a rigid adherend by a viscoelastic adhesive layer.For solving this problem, we use the principle of minimum free energy and derive a new energy criterion of the detachment. We propose a model of an aging viscoelastic material describing the viscoelastic behavior in terms of elastic objects. Using this model we propose an expression for the specific potential energy of an aging viscoelastic medium and derive a new formulation of the principle of minimum free energy for a viscoelastic system.A numerical method for solving nonlinear integro-differential equations describing the detachment process is developed, and its convergence is established. We analyze numerically the dependence of the detachment on the construction and material parameters, and on the loading history. We demonstrate the existence of a limited training effect, which allows considerable reduction of the detachment zone by a special preliminary loading program (“training”).     

储能飞轮转子轴承系统动力学设计与试验研究

飞轮储能系统通过飞轮升速和降速来实现电能储存和释放,研究飞轮转子轴承系统固有频率预计、临界转速设计、动平衡等动力学问题。采用永磁轴承与螺旋槽动压轴承的混合支承方式,建立储能飞轮强度、动力学和充放电特性试验研究装置,进行了动平衡、阻尼支承调整、飞轮储能系统损耗和发电量测试等试验,试验飞轮达到设计转速42.0 kr/min,总储能497 W·h,从42.0 kr/min降速到13.8 kr/min,可用放电能达到290 W·h。     

基于平均功率平衡控制的磁悬浮分子泵电力失效补偿方法

高速磁悬浮涡轮分子泵（Turbo Molecular Pump, TMP）因其高能量密度、微振动、无需润滑等优点被广泛应用于工业领域,但外部电源失效时,高速转子跌落后与保护轴承产生剧烈撞击和摩擦,将给系统带来致命损害。针对以上问题,提出一种基于平均功率平衡法的电力失效补偿控制（Power Failure Compensation Control, PFCC）方法。首先,设计电机能量回馈电路;其次,对Buck-Boost变换器进行数学建模,设计一种双环非线性控制器,其中电流内环使用滑模控制,电压外环使用平均功率平衡控制（Average Power Balance Control, APBC）,并利用Lyapunov函数推导出系统的稳定性条件;最后,通过搭建磁悬浮分子泵PFCC实验平台,对所提出的方法进行实验验证。结果表明：本文所提出的方法具有快速响应和输出鲁棒性,磁悬浮转子由额定转速21000 r/min降至3900 r/min时跌落,电机能量转化效率为96.6%,提高了磁轴承系统的安全性。