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Search Results: 1 - 10 of 111029 matches for " 何立东 "
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蜂窝密封动力特性系数的计算方法
张强,
中国电机工程学报 , 2007,
Abstract: 文中提出了一种计算直通型蜂窝密封动力特性系数的方法。该方法借助单控制体模型得到控制方程,将扰动变量代入控制方程得到零阶和一阶方程,最终由压力分布表达式推导出动力特性系数。通过简化一阶方程解的表达式、引入拉式变换和泰勒展开等数学手段极大地简化了计算,提高了计算速度。使用该方法所得到的动力特性系数的计算结果与测量值量级相同。在分析体现蜂窝密封对转子稳定性总体影响的有效阻尼时,采用该方法得到的计算结果与测量值非常接近。计算实例表明,应用文中所述方法所得计算结果可以用于定量地说明蜂窝密封的减振效果,该计算方法切实可行。
蜂窝密封流场旋涡能量耗散的数值研究
李金波,
中国电机工程学报 , 2007,
Abstract: 文中采用商业CFD软件建立有限元模型,并采用k-e两方程湍流模式求解了蜂窝密封的流动特性。从能量转化的角度分析解释了蜂窝密封具有良好封严特性的原因。计算结果表明,由于蜂窝密封特殊六边形结构将泄漏流体分割成小涡流,更有效地将气体能量转化为热能,从而减小泄漏;梳齿密封由于环向流动存在,削弱了能量耗散,泄漏量比较大。同时说明合适的蜂窝芯格尺寸和蜂窝深度会提高能量耗散,达到最佳的封严效果。文中的研究成果为透平机械中应用蜂窝密封提供了理论依据和技术支持。
基于相位补偿的电动助力转向系统控制方法
,
交通运输工程学报 , 2007,
Abstract: 采用动力学与控制理论,研究了具有3个集中质量的电动助力转向系统的物理和数学模型,建立了总体结构图,在对外环特性进行分析的基础上,对总体结构图进行等效变换,根据系统要求对控制系统进行了设计,研究了控制对象的传递函数、控制系统的结构图、开环系统的Bode图、Nyquist图以及系统的稳定性,并进行了台架试验。研究发现控制系统的结构图可以表示为内、外两环结构,内环包含了反电动势的反馈通道,采用快速比例积分(PI)控制的内环,可以忽略反电动势,没有进行相位补偿的系统幅值裕度和相位裕度约为负值,稳定性较差,而进行相位补偿后系统的稳定性较好。结果表明在系统低频共振频率范围内采用超前校正,提供相位补偿是解决电动助力转向系统振动和稳定性的有效方法。
磁流变阻尼器多目标靶向抑制四跨转子轴系过临界转速振动实验研究
杨秀峰,
- , 2017, DOI: 10.13543/j.bhxbzr.2017.02.015
Abstract: 针对四跨转子轴系过临界转速易发生振动过大且各跨转子之间耦合振动复杂的问题,研究了基于磁流变阻尼器的多目标靶向在线振动控制方法。搭建四跨转子轴系实验台,设计新型磁流变阻尼器并应用于自主开发的多目标靶向在线控制系统。模拟试车过程,研究了通入磁流变阻尼器内不同大小电流时,四跨转子轴系各跨转子振动的变化情况;由于四跨转子轴系过临界转速时耦合振动剧烈,因此提出基于转速的多目标靶向在线控制方法,采用在轴系中各跨转子临界转速附近开启、非临界转速关闭阻尼器的靶向分段控制策略,来实现在线抑制转子轴系过各阶临界转速时的振动。结果表明:磁流变阻尼器能抑制各跨转子过临界转速时的振动,且电流较大时抑振效果较好;应用带有多目标靶向在线控制系统的磁流变阻尼器能使四跨转子轴系在全转速范围振动较小,运行平稳。
Abstract:In view of the problem whereby four-span rotors vibrate excessively at the critical speed, a new type of magnetorheological (MR) damper has been designed and employed as a four-span rotor vibration control system. Its effect on the vibration of the rotors was studied in this work. Four-span rotor benches were built and MR dampers were installed on each span rotor corresponding to the original support mode. Experiments were carried out to verify the effect of vibration suppression with different currents in the damper. The results showed that the vibration of each span rotor at the critical speed can be suppressed effectively by the MR dampers, and the suppression increased with increasing current. Since the vibration of four-span rotors is usually too large around the critical speed, this causes the adjacent rotors to vibrate. A new multi-objective control method, in which the state of the damper was switched according to the speed, was constructed: at the critical speed the damper was turned on, and at lower speeds it was turned off. In this way, the vibration of the four-span rotors can be suppressed online. The results showed that the vibration of the four-span rotors was suppressed to an even greater extent by employing the dampers together with with multi-objective control system.
回转式空气预热器接触式柔性密封模拟分析
王庆峰,,张强
中国电机工程学报 , 2008,
Abstract: 针对回转式空气预热器的泄漏问题,提出了一种接触式柔性密封。接触式柔性密封的结构参数包括厚度、波数、波距、波深、初始伸长、总长和迎角,刚度是接触式柔性密封的重要性能参数。从基本力学模型出发,运用有限元方法对不同结构参数下的接触式柔性密封进行模拟分析,得到相应结构参数的最大载荷、载荷-位移关系和各结构参数-刚度关系。运用多元逐步回归分析,得出厚度、波深和波数对刚度具有预测意义,其中以厚度的预测性最高。
转子动力吸振器在线抑制多跨转子过临界振动的实验研究
王晨阳,
中国电机工程学报 , 2015, DOI: 10.13334/j.0258-8013.pcsee.2015.18.019
Abstract: 为解决多跨转子系统通过临界转速时振动过大的问题,搭建双跨和三跨转子实验台,设计了新型转子动力吸振器,在轴上安装转子动力吸振器,模拟转子试车过程。通过基于转速的开关控制,在线控制转子动力吸振器中电磁铁的吸合状态,使其固有频率在2个频率之间切换,其中1个频率高于转子工作转速对应的频率,另1个频率与转子临界转速对应频率一致。对双跨转子和三跨转子轴系进行了带有开关控制的转子动力吸振器振动控制研究。结果表明,转子动力吸振器不仅能够在线抑制双跨转子和三跨转子轴系通过临界转速时的剧烈振动,还能避免使用传统动力吸振器给转子轴系带来2个新的共振峰的弊端,使转子系统在全转速范围内都能保持较低振动水平。
基于ansys的回转式空气预热器接触式柔性密封疲劳寿命分析
王庆峰,
热力发电 , 2010,
Abstract: 基于有限元通用软件ansys的疲劳寿命分析方法,运用ansys的fatigue模块,将有限元方法和疲劳寿命分析理论相结合,对回转式空气预热器接触式柔性密封进行三维参数化建模,并编制apdl命令流,建立疲劳分析文件对回转式空气预热器接触式柔性密封进行了疲劳寿命分析。结果表明,回转式空气预热器接触式柔性密封的疲劳寿命为8年。
磁流变液对转子系统的影响规律实验研究
胡航领,
- , 2016, DOI: 10.13543/j.bhxbzr.2016.02.014
Abstract: 针对磁流变阻尼器能够通过变刚度和变阻尼实现半主动控制,搭建单跨转子实验台,将磁流变阻尼器作为辅助装置安装于转子跨内,通过实验研究阻尼器内磁流变液对转子系统的影响规律。结果表明,阻尼器通电状况下,使用的磁流变液质量比较小,即铁粉占比较大时,阻尼器可等效为刚性支撑,为转子提供刚度,并改变其临界转速;阻尼器使用的磁流变液质量比增大到一定程度时,阻尼器为转子提供阻尼,能有效抑制转子振动;质量比继续增大,则振动降幅随之减小;磁流变液所用硅油黏度增大时,阻尼器对转子系统振动的抑制作用增强。
Abstract:Magneto-rheological dampers can be semi-actively controlled by changing the stiffness or damping. A single-span rotor bench was established to simulate the starting process. A magneto-rheological damper was installed at middle of the inside part of the shaft. The influence of the magneto-rheological fluid on rotor system was studied. The results showed that the damper can be regarded as a rigid support when the mass ratio of the magneto-rheological fluid is small, namely when there is a large proportion of iron powder in the magnet-rheological fluid. The damper provides stiffness for the rotor and the critical speed of the rotor is changed. The damper converts a rigid support into an elastic support when the mass ratio increases to a certain value and the damper provides damping for the rotor. The effect is weaker when the mass ratio is bigger. The reduction in the vibration of the rotor system is better when the viscosity of the silicone oil is higher.
基于磁流变阻尼器的双跨轴系PID振动控制研究
郭咏雪,,王锎
- , 2018, DOI: 10.13543/j.bhxbzr.2018.03.010
Abstract: 为了解决双轴串联的旋转机械在临界转速处产生共振问题,搭建了双跨转子实验台,在不改变原有支撑形式的条件下将磁流变阻尼器分别安装在串联的轴1、轴2上,并建立双跨轴系振动的半主动控制系统,采用比例-积分-微分(PID)控制方法,以振幅为反馈参数实时调节阻尼器电流,在线抑制双跨轴系的振动,并在此基础上通过整定PID控制的比例系数K研究其值对振动控制效果的影响。实验结果表明:基于磁流变阻尼器的PID控制系统可以有效控制两个串联轴在临界转速附近的振动;对临界振幅过大的转子宜采用较大K值,而对临界振幅较小的转子可适当减小K值。
Abstract:In order to study the vibration problems of rotating machinery consisting of a two-span shaft around its critical speeds, a two-span rotor test rig was built, and two magneto-rheological dampers were installed on the two coupled rotors without changing the original support. Subsequently, by incorporating a proportion-integration-differentiation (PID) control method, a semi-active control system for the two-span rotor system vibration was established. Using vibration amplitude as the feedback parameter, the system controlled the electric currents of the magneto-rheological at any time allowing the rotor system vibration to be controlled online. In addition, in order to study how the proportionality coefficient influences the control effect, the value of K was varied. The experimental results indicated that the PID control system based on magneto-rheological dampers can successfully suppress the vibration of the two coupled rotors at their critical speeds. For higher values of K, the control effect is better, but very large values of K make the control effect worse. Therefore K should be large in the case of a rotor with a large critical vibration and smaller in the case of a rotor with a smaller critical vibration.
压差对旋转直通式迷宫气封流场及流场力影响规律研究
王庆峰,
- , 2018, DOI: 10.13543/j.bhxbzr.2018.04.011
Abstract: 基于稳态计算流体动力学(CFD)方法,研究了压差对旋转直通式迷宫气封泄漏、流场和流场力的影响。通过网格密度分析验证了稳态CFD方法满足计算精度要求,通过影响和敏感度分析给出了压差的变化对泄漏量、流场速度流线、总压强分布、流体压力和流体粘滞力的影响。研究结果表明:随着压差的增大,泄漏量、径向流体压力、轴向流体压力、总流体压力、径向流体粘滞力、轴向流体粘滞力和总流体粘滞力均增大。
Abstract:The effects of the pressure drop on the leakage, flow field and fluid-induced force of a rotary straight-through labyrinth gas seal have been investigated using a steady-CFD analysis method. The grid density analysis ensures that the steady-CFD analysis method meets the requirements of calculation precision. The effect and sensitivity analyses show that the changes in pressure drop affect the leakage flow rates, velocity streamlines, total pressure distributions, pressure forces, and viscous forces. The results indicate that increasing the pressure drop increases the leakage flow rates, axial pressure forces, radial pressure forces, total pressure forces, axial viscous forces, radial viscous forces and total viscous forces.
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