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为研究双稳态压电俘能系统的相关特性,首先,建立了外界激励作用下双稳态压电悬臂梁俘能系统的等效数学模型;其次,运用谐波平衡法计算获得了系统的动力响应方程,通过绘制的动力响应曲线发现了系统中幅值与功率的解均存在跳跃现象和多解的不稳定区域;最后,分析比较了不同参数对系统动力响应的影响特性。研究结果为优化双稳态压电悬臂梁俘能器的设计和应用提供了理论依据。 相似文献
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齿轮—转子—滑动轴承系统时变非线性动力特性研究 总被引:4,自引:0,他引:4
本文应用求周期解的数值计算方法-打靶法和判定周期解稳定性的Floquet乘子研究了齿轮-转子-滑动轴承系统中齿轮啮合时变刚度,滑动轴承非线性特性对转子系统不平衡响应和失稳的影响,并比较了平衡位置失稳和不平均响应周期解失稳,以及按双轴计算与单轴计算结果的差别,为工程设计理论计算提供基础。 相似文献
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本文提出了通过逐次将非线性力等效线性化,然后用具有许多优点的 Prohl 法计算等效系统响应的迭代法,用以求非线性转子系统的稳态不平衡响应.实例计算了装有中介轴挤压油膜阻尼器的双转子发动机的稳态不平衡响应. 相似文献
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求解转子系统突加不平衡响应方法的研究 总被引:4,自引:0,他引:4
本文提出并研究了用传递函数分析法求转子系统的突加不平衡响应,讨论了求这一响应的最佳数值积分方法。用本文提出的理论解方法及三种常用的数值积分法:尤拉后差法,纽马克法,及呼伯特法,对一模型转子算例进行了分析计算,结果表明;尤拉后差法最适用于求转子系统的突加不平衡响应。本文提出的传递函数分析法,可以和试验模态分析方法相结合,以求解复杂转子系统的突加不平衡响应。 相似文献
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非线性系统周期强迫不平衡响应的稳定性分析 总被引:4,自引:0,他引:4
多自由度强非线性系统是工程实际中经常遇见的一类模型,利用非线性动力学分析中的打靶法求解该类系统的周期解,并对Flopuet主导特征值判断周期解的失稳方式,利用该方法对旋转机械中的一个具体模型;双盘县臂柔性转子-非同心型挤压油膜阻尼器(SFD)系统周期强迫不平衡响应的稳定性和分岔行为进行了分析,分析表明,在该系统中存在着第二Hopf分岔、倍周期分岔、鞍-结分岔三种分岔形式。 相似文献
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考虑桩土相互作用效应的桩顶纵向振动时域响应分析 总被引:6,自引:0,他引:6
在考虑桩土耦合作用以及土竖向波动效应条件下,对均质滞回材料阻尼土中弹性支承桩桩顶纵向振动时域响应进行了理论研究。首先建立了桩与滞回阻尼土在谐和振动情况下的定解问题,然后先对土层动力平衡方程进行求解并得到土体振动位移形式解,接着依据平衡条件将该形式解祸合进桩身动力平衡方程,并通过对桩动力平衡方程的求解,最终得到桩顶位移和速度频域响应解析解和半正弦脉冲激励作用下桩顶时域响应的半解析解。通过与其它相关理论解的对比验证了本文解的正确性和适用性,并基于所得解对桩顶时域响应特性进行了分析,最后将理论曲线与现场工程实测曲线进行了拟合对比,结果表明两者符合较好。 相似文献
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涡轮泵转子-迷宫密封系统的非线性稳定性和分岔 总被引:2,自引:0,他引:2
研究迷宫密封对某一工程涡轮泵转子系统动力特性的影响,迷宫密封力采用Muszynska非线性力模型,应用有限元法建立转子系统的动力学方程,采取系统动力学方程中包含的高阶线性自由度和低阶的非线性自由度进行分块处理的方法,有效地缩短了求解时间。根据Floquet理论,判别系统的临界失稳转速,并由Floquet乘子来确定系统失稳后分岔方式。采用分块-Newmark法数值模拟了转子二涡轮盘的轴心轨迹。最后分析了涡轮泵转子二涡轮盘的质量偏心同相位和存在90度相位差时对转子系统运动特性的影响。 相似文献
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P. N. Jiang W. Z. Wang Y. Z. Liu G. Meng 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(2):177-189
A comparative analysis of the influence of steam leakage through vane, gland, and shaft seals on the rotordynamics of the
high-pressure rotor of a 1,000 MW ultra-supercritical steam turbine was performed using numerical calculations. The rotordynamic
coefficients associated with steam leakage through the three labyrinth seals were calculated using the control-volume method
and perturbation analysis. A stability analysis of the rotor system subject to the steam forcing induced by the leakage flow
was performed using the finite element method. An analysis of the influence of the labyrinth seal forcing on the rotordynamics
was carried out by varying the geometrical parameters pertaining to the tooth number, seal clearance, and inner diameter of
the labyrinth seals, along with the thermal parameters with respect to pressures and temperatures. The results demonstrated
that the steam forcing with an increase in the length of the blade for the vane seal significantly influences the rotordynamic
coefficients. Furthermore, the contribution of steam forcing to the instability of the rotor is decreased and increased with
increases in the seal clearance and tooth number, respectively. The comparison of the rotordynamic coefficients associated
with steam leakage through the vane seal, gland seal, and shaft seal convincingly disclosed that, although the steam forcing
attenuates the stability of the rotor system, the steam turbine is still operating under safe conditions. 相似文献
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The influence of labyrinth seal on the stability of unbalanced rotor system was presented . Under the periodic excitation of rotor unbalance , the whirling vibration of rotor is synchronous if the rotation speed is below stability threshold, whereas the vibration becomes severe and asynchronous which is defined as unstable if the rotation speed exceeds threshold . The. Muszynska model of seal force and shooting method were used to investigate synchronous solution of the dynamic equation of rotor system. Then , based on Floquet theory the stability of synchronous solution and unstable dynamic characteristic of system were analyzed. 相似文献
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建立超临界二氧化碳(supercritical carbon dioxide,SCO2)高低齿梳齿密封三维数值计算模型,应用基于微元理论的密封动特性识别方法,研究凸台宽度及密封间隙对超临界二氧化碳梳齿密封动静特性的影响,并与传统梳齿密封进行对比. 研究表明:高低齿梳齿密封的交叉复合刚度系数对有效阻尼系数影响较小,主阻尼对其占主要影响. 在低涡动频率下(<160 Hz),传统梳齿密封动力稳定性较好;而涡动频率高于160 Hz时,高低齿梳齿密封的有效阻尼系数约为传统梳齿密封的105%~113%;且存在1个最佳凸台宽度使密封系统稳定性最好(本文最佳值为5.13 mm);随着密封间隙的减小,有效阻尼系数的大小与频率依赖性分别增大、增强. 高低齿梳齿密封泄漏量较传统梳齿密封降低约45.5%;凸台宽度5.13 mm、密封间隙0.4 mm时较原始模型(b=4 mm、c2=0.5 mm)泄漏量分别降低约5%和19%,高低齿梳齿密封泄漏量随密封间隙的减小而降低. 相似文献
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W. Z. Wang Y. Z. Liu H. P. Chen P. N. Jiang 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(8):587-597
A mathematical model of calculating rotordynamic coefficients associated with leakage steam flow through labyrinth seals was
presented. Particular attention was given to incorporating thermal properties of the steam fluid into prediction of leakage
flow and subsequent derivation of rotordynamic coefficients, which quantitatively characterize influence of aerodynamic forcing
of the leakage steam flow on the rotordynamics. By using perturbation analysis, we determined periodic and analytic solutions
of the continuity and circumferential momentum equations for the time-dependent flow induced by non-axisymmetric rotation
of the rotor encompassed by a labyrinth seal. Pressure distributions along labyrinth seal cavities and rotordynamic coefficients
were compared at the same condition for air and steam flows. Influence of steam flow through the labyrinth seal cavities on
rotordynamic coefficients was analyzed in terms of inlet pressure, inlet swirl velocity and rotor speed. 相似文献
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Nonlinear dynamics and stability of the rotor–bearing–seal system are investigated both theoretically and experimentally. An experimental rotor–bearing–seal device is designed and corresponding tests are carried out. The experimental rotor system is simplified as the Jeffcott rotor. The nonlinear oil–film forces are obtained under the short bearing theory and Muszynska nonlinear seal force model is used. Numerical method is utilized to solve the nonlinear governing equations. Bifurcation diagrams, waterfall plots, Poincaré maps, spectrum plots and rotor orbits are drawn to analyze various nonlinear phenomena and system unstable processes. Theoretical results from numerical analysis are in good agreement with results from experiments. Conclusions are drawn and prove that this study will contribute to the further understanding of nonlinear dynamics and stability of the rotor system with the fluid-induced forces from oil–film bearings and the seals. 相似文献
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A nonlinear mathematical model for orbital motion of the rotor under the influence of leakage flow through a labyrinth seal was established in the present study. An interlocking seal was chosen for study. The rotor–seal system was modeled as a Jeffcot rotor subject to aerodynamic forcing induced by the leakage flow. Particular attention was placed on the serpentine flow path by spatially separating the aerodynamic force on the rotor surface into two parts, e.g., the seal clearance and the cavity volume. Spatio-temporal variation of the aerodynamic force on the rotor surface in the coverage of the seal clearance and the cavity volume was delineated by using the Muzynska model and perturbation analysis, respectively. The governing equation of rotor dynamics, which was incorporated with the aerodynamic force integrated over all seal clearances and cavity volumes, was solved by using the fourth-order Runge–Kutta method to obtain the orbit of the whirling rotor. Stability of the rotating rotor was inspected using the Liapunov first method. The results convincingly demonstrate that the destabilization speed of the rotor was reduced due to the aerodynamic force induced by the leakage flow through the interlocking seal. The nonlinear analysis method proposed in the present study is readily applied to dynamics of various rotor–seal systems with labyrinth seals. 相似文献
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Nonlinear dynamic behaviors of a rotor-labyrinth seal system 总被引:2,自引:0,他引:2
The nonlinear model of rotor-labyrinth seal system is established using Muszynska’s nonlinear seal forces. We deal with dynamic
behaviors of the unbalanced rotor-seal system with sliding bearing based on the adopted model and Newmark integration method.
The influence of the labyrinth seal one the nonlinear characteristics of the rotor system is analyzed by the bifurcation diagrams
and Poincare’ maps. Various phenomena in the rotor-seal system, such as periodic motion, double-periodic motion, quasi-periodic
motion and Hopf bifurcation are investigated and the stability is judged by Floquet theory and bifurcation theorem. The influence
of parameters on the critical instability speed of the rotor-seal system is also included. 相似文献
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Using a flexible support is an efficient approach to solving the subsynchronous problems in a turbopump. In this paper, nonlinear rotordynamic analysis of a liquid fuel turbopump with a flexible support is presented using a dynamic modeling including two key destabilizing factors, nonlinear hydrodynamic forces induced by seals and internal rotor damping. The methodology of the partitioned direct integration method (PDIM) is described for reducing the computational efforts efficiently. Combining the PDIM and the shooting method, a nonlinear stability analysis of the rotor system is performed effectively. The numerical results, which are in good agreement with test data, indicate that the effects of flexible support stiffness k on the dynamic characteristics and stability of the rotor system are significant. The first critical speed of the rotor system rises as a nonlinear function of k markedly. The second critical speed varies slightly and approximates a linear variation as k increases. The onset speed of instability of the rotor system rises initially and then reduces as k increases. The effect of seal nonlinearities at low k is contrary to that at high k and the effect of seal length on the system stability is more significant than that of seal radius. The results explain the nature of the subsynchronous motion of a turbopump rotor system with flexible support and can be used in the design and operation of a liquid fuel turbopump rotor system to eliminate its rotordynamic problem. 相似文献