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1.
四瓦可倾瓦径向滑动轴承动力特性的实验研究 总被引:2,自引:0,他引:2
采用在线分析方法考察了300MW汽轮发电机可倾瓦轴承的静、动力特性,探讨了载荷、轴颈转速以及动态激振力频率等参数变化对可倾瓦轴承的静、动态性能的影响,比较试验结果与理论计算结果发现,在不同频率激振力作用下,理论计算所得到的可倾瓦轴承动特性参数与试验结果有较大的差异。 相似文献
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基于可倾瓦径向滑动轴承瓦块的扰动特性,提出了计算轴承完整动力系数的数学解析模型。在由单块瓦和轴颈构成的子系统上建立局部动坐标参考系,全局广义位移向量可以通过简练的步骤转换为局部动坐标系下轴颈的位移向量,利用求解固定瓦轴承动力特性的方法求得的局部动坐标系下的油膜力又可以精确地转换为全局坐标系下的表达形式,全局坐标系下的油膜力向量关于广义位移和广义速度的Jocabian矩阵形成轴承的完整动力特性系数;利用Newton-Raphson方法同时求解瓦块和轴颈在给定的静态载荷下的平衡位置,其中所需用到的系数矩阵恰好为轴承油膜力关于广义位移的Jocabian矩阵的负值,在得到平衡位置的同时可以获得轴承完整的刚度和阻尼矩阵。数值算例证明了此方法的有效性。 相似文献
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转子—非线性支承系统振动响应的优化计算 总被引:1,自引:0,他引:1
本文用一种新的优化方案计算装有非线性弹性支承-挤压油膜阻尼器的转子系统的振动响应。首先根据转子系统的结构特点,建立其无量纲形式的非线性运动微分方程;然后由微分方程构造-控制目标函数,最后对此目标函数进行优化计算,求得转子系统的振动响应。 相似文献
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本文中建立了水润滑可倾瓦推力轴承启停过程瞬态模型,采用Hertz接触模型,以自定义可倾瓦推力轴承起动过程发生初始倾斜时刻转速—初始倾斜转速Uft为对象,分析了支点接触与磨损变形量、载荷大小对水润滑可倾瓦推力轴承起动过程影响.初始倾斜转速Uft随着支点变形量增大而增大,随着载荷增大而增大.在给定可倾瓦推力轴承可接受初始倾斜转速最大值Uftc情况下,几何尺寸确定可倾瓦推力轴承载荷及支点变形均存在最大值.采用水润滑可倾瓦推力轴承性能试验台进行模型验证,结果表明:Uft测量值与数值分析结果吻合度较高,误差小于10%;采用加速度传感器及扭矩传感器联合方法可以比较准确地判断出轴承推力瓦发生倾斜时刻,从而确定可倾瓦推力轴承的Uft值. 相似文献
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This experimental investigation concerns the static and dynamic behaviour of a rigid balanced rotor on journal bearings. Running conditions were chosen in order to obtain relatively high eccentricity ratios near the instability threshold speeds.The results, compared also with the theoretical predictions of some authors, have substantially shown the importance of examining the static behaviour near the instability threshold speed to allow a correct interpretation of some aspects of the dynamic behaviour.In order to clarify the discrepancies between the observed and the theoretically predicted dynamic behaviour, some further tests have been carried out.
Sommario E' stato esaminato sperimentalmente sia il comportamento statico che quello dinamico di un rotore rigido e bilanciato sostenuto da cuscinetti cilindrici lubrificati.Le condizioni di funzionamento sono state scelte in modo tale che, in prossimità della soglia di instabilità, il valore del rapporto di eccentricità risultasse relativamente grande.I risultati, confrontati anche con le indicazioni teoriche di altri autori, hanno sostanzialmente evidenziato l'importanza dell'esame del comportamento statico in prossimità della soglia di instabilità al fine di interpretare correttamente alcuni aspetti del fenomeno dell'instabilità.Sono state inoltre effettuate una serie di ulteriori indagini con lo scopo di chiarire le discordanze fra il comportamento dinamico osservato e quello previsto dalla teoria.相似文献
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Chaotic motions of a rigid rotor in short journal bearings 总被引:65,自引:0,他引:65
In the present paper the conditions that give rise to chaotic motions in a rigid rotor on short journal bearings are investigated and determined. A suitable symmetry was given to the rotor, to the supporting system, to the acting system of forces and to the system of initial conditions, in order to restrict the motions of the rotor to translatory whirl. For an assigned distance between the supports, the ratio between the transverse and the polar mass moments of the rotor was selected conveniently small, with the aim of avoiding conical instability. Since the theoretical analysis of a system's chaotic motions can only be carried out by means of numerical investigation, the procedure here adopted by the authors consists of numerical integration of the rotor's equations of motion, with trial and error regarding the three parameters that characterise the theoretical model of the system: m, the half non-dimensional mass of the rotor, , the modified Sommerfeld number relating to the lubricated bearings, and , the dimensionless value of rotor unbalance. In the rotor's equations of motion, the forces due to the lubricating film are written under the assumption of isothermal and laminar flow in short bearings. The number of numerical trials needed to find the system's chaotic responses has been greatly reduced by recognition of the fact that chaotic motions become possible when the value of the dimensionless static eccentricity % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbnL2yY9% 2CVzgDGmvyUnhitvMCPzgarmWu51MyVXgaruWqVvNCPvMCG4uz3bqe% fqvATv2CG4uz3bIuV1wyUbqee0evGueE0jxyaibaieYlf9irVeeu0d% Xdh9vqqj-hEeeu0xXdbba9frFf0-OqFfea0dXdd9vqaq-JfrVkFHe9% pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaaca% qabeaadaabauaaaOqaaiabew7aLnaaBaaaleaacaWGZbaabeaaaaa!4046!\[\varepsilon _s \] is greater than 0.4. In these conditions, non-periodic motions can be obtained even when rotor unbalance values are not particularly high (=0.05), whereas higher values (>0.4) make the rotor motion periodic and synchronous with the driving rotation. The present investigation has also identified the route that leads an assigned rotor to chaos when its angular speed is varied with prefixed values of the dimensionless unbalance . The theoretical results obtained have then been compared with experimental data. Both the theoretical and the experimental data have pointed out that in the circumstances investigated chaotic motions deserve more attention, from a technical point of view, than is normally ascribed to behaviours of this sort. This is mainly because such behaviours are usually considered of scarce practical significance owing to the typically bounded nature of chaotic evolution. The present analysis has shown that when the rotor exhibits chaotic motions, the centres of the journals describe orbits that alternate between small and large in an unpredictable and disordered manner. In these conditions the thickness of the lubricating film can assume values that are extremely low and such as to compromise the efficiency of the bearings, whereas the rotor is affected by inertia forces that are so high as to determine severe vibrations of the supports.Nomenclature
C
radial clearance of bearing (m)
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D
diameter of bearing (m)
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e
dimensional eccentricity of journal (m)
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e
s
value of e corresponding to the static position of the journal
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E
dimensional static unbalance of rotor (m)
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f
x, f
y =F
x/(P), F
y/(P):
non-dimensional components of fluid film force
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F
x,
F
y dimensional components of fluid film force (N)
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g
acceleration of gravity (m/s2)
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L
axial length of bearing (m)
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m
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbnL2yY9% 2CVzgDGmvyUnhitvMCPzgarmWu51MyVXgaruWqVvNCPvMCG4uz3bqe% fqvATv2CG4uz3bIuV1wyUbqee0evGueE0jxyaibaieYlf9irVeeu0d% Xdh9vqqj-hEeeu0xXdbba9frFf0-OqFfea0dXdd9vqaq-JfrVkFHe9% pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaaca% qabeaadaabauaaaOqaaiabg2da9maalaaabaGaeqyYdC3aaWbaaSqa% beaacaaIYaaaaaGcbaGaeqyYdC3aa0baaSqaaGabciaa-bdaaeaaca% WFYaaaaaaakiabg2da9maalaaabaGaeqyYdC3aaWbaaSqabeaacaaI% YaaaaOGaam4qaaqaaiabeo8aZjaadEgaaaaaaa!4C14!\[ = \frac{{\omega ^2 }}{{\omega _0^2 }} = \frac{{\omega ^2 C}}{{\sigma g}}\]: half non-dimensional mass of rotor
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M
half mass of rotor (kg)
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n
angular speed of rotor (in r.p.m.=60/2)
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t
time 相似文献
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An analytical model of a tilting pad bearing was developed based on the short bearing assumption with the turbulence effect
included. In order to determine its influence on the dynamic behavior of the rotor, this model was compared against one without
the turbulence effect through a simulation of a Jeffcott/Laval rotor supported by a couple of bearings. Both models were also
used to determine the influence of geometric parameters on tilting pad bearing making use of the aforementioned system at
different rotor speeds.
When analyzing the results, the parameters which presented the largest influence were: pad preload, number of segments, radial
clearance, pad position, and pad pivoting angle. As the pad moment of inertia and the pivoting distance have changed the shaft
motion only a few microns, their effects can be neglected. The bearing model with turbulent flow effect has generated higher
hydrodynamic forces when compared to the one without this effect, which remarks the importance of considering such phenomenon
during the analysis of the high speed hydrodynamic bearings. 相似文献
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Nonlinear Dynamics - Porous tilting pad bearings (PTPBs) combine the advantages of tilting pad and porous gas bearings and can be used in rotary motion and precision machine tools. This research... 相似文献
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In this paper, the Riccati transfer matrix method and the component theory of forward and backward whirls are used to the eigenproblem of damped free whirling vibration of a flexible rotor with arbitrarily distributed mass on isotropic or anisotropic supports, with the gyroscopic effect taken into account to find out its critical speeds and corresponding vibrational shape functions. The generalized damped mode theory is developed and extended, which is employed in combination with the Bogoliubov-Mitropolskii asymptotic method to deduce two sets of first order differential equations to calculate the transient response of the rotor with limited power supply passing through its critical speeds in forward whirl and backward whirl respectively. The coupling phenomenon of the rotor through two neighboring critical speeds is also analyzed. 相似文献
16.
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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Bifurcation and chaotic response of a cracked rotor system with viscoelastic supports 总被引:1,自引:0,他引:1
Cracks appearing in the shaft of a rotary system are one of the main causes of accidents for large rotary machine systems.
This research focuses on investigating the bifurcation and chaotic behavior of a rotating system with considerations of various
crack depth and rotating speed of the system’s shaft. An equivalent linear-spring model is utilized to describe the cracks
on the shaft. The breathing of the cracks due to the rotation of the shaft is represented with a series truncated time-varying
cosine series. The geometric nonlinearity of the shaft, the masses of the shaft and a disc mounted on the shaft, and the viscoelasticity
of the supports are taken into account in modeling the nonlinear dynamic rotor system. Numerical simulations are performed
to study the bifurcation and chaos of the system. Effects of the shaft’s rotational speed, various crack depths and viscosity
coefficients on the nonlinear dynamic properties of the system are investigated in detail. The system shows the existence
of rich bifurcation and chaos characteristics with various system parameters. The results of this research may provide guidance
for rotary machine design, machining on rotary machines, and monitoring or diagnosing of rotor system cracks. 相似文献
18.
The nonlinear dynamic behavior of a rigid rotor supported by a spherical gas journal bearing system is analyzed using a hybrid
method combining the differential transformation method (DTM) and the finite difference method (FDM). The analytical results
reveal that the bearing system has a complex dynamic behavior comprising periodic, subharmonic, and quasi-periodic responses
of the rotor center. The evolution in the dynamic behavior of the bearing system is systematically examined as the rotor mass
and bearing number are increased. The analytical results are found to be in good agreement with those of other numerical methods.
Hence, the validity of the proposed hybrid method as a means of gaining insights into the nonlinear dynamics of spherical
gas film rotor-bearing systems is confirmed. 相似文献