scholarly journals Mathematical Modelling of Dynamic System Rotor-Groove Seals for the Purposes of Increasing the Vibration Reliability of NPP Pumps

2021 ◽  
pp. 80-87
Author(s):  
S. Shevchenko ◽  
O. Shevchenko ◽  
S. Vynnychuk
Keyword(s):  
Mathematical Modelling ◽  
Dynamic System ◽  
Dynamic Characteristics ◽  
Frequency Characteristics ◽  
Centrifugal Machine ◽  
Hydrostatic Bearings ◽  
Radial Forces ◽  
Vibration Reliability ◽  
Pumping Equipment ◽  
Rotor Model

Groove seals are considered as hydrostatic bearings capable of effectively damping rotor vibrations. In order to determine the dynamic characteristics, a model of the rotor-groove seals system is considered. The radial forces and moments in groove seals had been estimated. Expressions of joint radial-angular rotor vibrations in groove seals had been obtained. Formulas had been proposed for constructing amplitude and phase frequency characteristics. An example of calculating the dynamic characteristics of a centrifugal machine rotor model is presented. The directions of increasing the vibration reliability of NPP pumping equipment by purposefully increasing the rigidity of groove seals are determined.

scholarly journals Mathematical Modelling of Dynamic System Rotor – Groove Seals

2021 ◽  
Vol 43 (3) ◽  
pp. 17-35
Author(s):  
S.S. Shevchenko ◽  
Keyword(s):  
Mathematical Modelling ◽  
Dynamic System ◽  
Dynamic Characteristics ◽  
Frequency Characteristics ◽  
Centrifugal Machine ◽  
Hydrostatic Bearings ◽  
Radial Forces ◽  
Rotor Model

Groove seals are considered as hydrostatic bearings that capable of effectively damping rotor vibrations. In order to determine the dynamic characteristics, a model of the rotor–groove seals system is considered. The radial forces and moments in groove seals had been estimated. Expressions of joint radial-angular rotor vibrations in groove seals had been obtained. Formulas had been proposed for constructing amplitude and phase frequency characteristics. An example of calculating the dynamic characteristics of a centrifugal machine rotor model is given.

Mathematical modeling of centrifugal machines rotors seals for the purpose of assessing their influence on dynamic characteristics

2021 ◽  
Vol 8 (3) ◽  
pp. 422-431
Author(s):  
S. S. Shevchenko ◽  
Keyword(s):  
Mathematical Modeling ◽  
Dynamic Characteristics ◽  
Frequency Characteristics ◽  
Shaft Rotation ◽  
Centrifugal Machine ◽  
Operational Safety ◽  
Angular Oscillations

With an increase of equipment parameters, such as the pressure of the sealing medium and the speed of shaft rotation, the problems ensuring its hermetization efficiency are rising up. In addition to hermetization itself, the sealing system affect the overall operational safety of the equipment, especially vibratory. Groove seals are considered as hydrostatodynamic supports capable of effectively damping rotor oscillations. To determine the dynamic characteristics, models of grooved seals and single-disc rotors with grooved seals are examined. The obtained analytical dependences for computation of dynamic characteristics for the hydromechanical rotor-seals system, describing radial-angular oscillations of the centrifugal machine rotor in groove seals are presented as well as the formulas for computation of amplitude frequency characteristics. An example for the computation dynamic characteristics of one of the centrifugal machine rotor models is drawn.

Numerical Investigation of Static and Dynamic Characteristics of Water Hydrostatic Porous Thrust Bearings

2011 ◽  
Vol 5 (6) ◽  
pp. 773-779 ◽  
Author(s):  
Yuki Nishitani ◽  
◽  
Shigeka Yoshimoto ◽  
Kei Somaya
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Measuring Equipment ◽  
Load Capacity ◽  
Damping Coefficient ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Hydrostatic Bearings ◽  
Aerostatic Bearings

A moving table supported by aerostatic bearings can achieve excellent accuracy of motion because of its noncontact support and, hence, it is used in various precision machine tools and measuring equipment. However, because of low viscosity of air, the damping coefficient of aerostatic bearings is not very high, causing vibration with nanometer-order amplitudes. The accuracy of machine tools and measuring equipment could deteriorate because of this vibration. It is expected that water hydrostatic bearings would have a higher damping coefficient than aerostatic bearings due to the higher viscosity of water. In addition, water, like air, does not pollute the environment. In this paper, the static and dynamic characteristics of water hydrostatic thrust bearings using porous material were numerically investigated and comparedwith conventional pocket hydrostatic bearings with a capillary restrictor. Hydrostatic porous bearings can be easily constructed because the porous material becomes a viscous restrictor itself. It was consequently found that water hydrostatic porous thrust bearings have higher maximum load capacity and slightly lower stiffness than water bearings with a capillary restrictor.

Dynamic characteristics of a resonant gas-dynamic system for ignition of a fuel mixture

2013 ◽  
Vol 49 (6) ◽  
pp. 657-661 ◽  
Author(s):  
K. Yu. Aref’ev ◽  
A. V. Voronetskii ◽  
M. A. Il’chenko
Keyword(s):  
Dynamic System ◽  
Dynamic Characteristics ◽  
Fuel Mixture ◽  
Gas Dynamic

Research on the Frequency Dynamic Characteristics and UFLS Scheme in Shanghai Subzone Power Grid

2013 ◽  
Vol 291-294 ◽  
pp. 2291-2297
Author(s):  
Wen Qing Yang ◽  
Wei Cao ◽  
Zhi Gang Ding
Keyword(s):  
Dynamic Characteristics ◽  
Power Grid ◽  
Peak Load ◽  
Frequency Characteristics ◽  
Power Grids ◽  
Load Shedding ◽  
Transient Simulation ◽  
Simulation Program ◽  
Equivalent Model ◽  
Ring Network

Shanghai main power grid is operating in 500 kV ring network and with voltage-grading & district-dividing structure, and its subzone power grids have their own frequency characteristics. The paper has used district-dividing single equivalent model to check the parameters of components in BPA transient simulation program, and the original under frequency load shedding (UFLS) scheme was improved. Then the frequency dynamic characteristics of isolated subzone grid is analyzed, so does the adaptability and frequency safety of power grid under the new UFLS scheme in the condition of peak load in the summer of 2011.

Optimal Pole Assignment of Self-Balancing Robot System

2012 ◽  
Vol 538-541 ◽  
pp. 2649-2653
Author(s):  
Yan Hua Zhao ◽  
Guo Zhang ◽  
Chun Xia Duan
Keyword(s):  
Optimal Design ◽  
Dynamic System ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic System ◽  
Pole Assignment ◽  
Real Time Control ◽  
Robot System ◽  
Time Control ◽  
Balancing Robot

Self-balancing robot is a multivariable, coupled, nonlinear dynamic system, using the optimal pole assignment which can give attention to both good dynamic characteristics and LQ optimal design technology robustness and other advantages. Emulation and real-time control are given to show the effectiveness of the presented method.

scholarly journals Dynamic characteristics of mean type dimension lathe installed on rubber-metal anti-vibration supports

2017 ◽  
Vol 2 (5) ◽  
pp. 26-30
Author(s):  
А. Денисенко ◽  
A. Denisenko
Keyword(s):  
Dynamic Model ◽  
Elastic Deformation ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Vibration Isolation ◽  
Elastic Characteristic ◽  
Frequency Characteristics ◽  
Experimental Dependence ◽  
Proof System ◽  
Nonlinear Dynamic Model

On the basis of a nonlinear dynamic model of a vibration-proof system at power excitation there are formed amplitude-frequency characteristics of a lathe installed on rubber-metal anti-vibration supports, and an area of efficient vibration isolation is defined. An elastic characteristic of the model is presented as an approximating dependence obtained on the basis of the experimental dependence of support elastic deformation changes upon loading.

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