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.

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.

Modified Reynolds Equation for Aerostatic Porous Radial Bearings With Quadratic Forchheimer Pressure-Flow Assumption

2007 ◽  
Author(s):  
Rodrigo Nicoletti ◽  
Zilda C. Silveira ◽  
Benedito M. Purquerio
Keyword(s):  
Mathematical Modeling ◽  
Porous Medium ◽  
Linear Model ◽  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Dimensional Parameter ◽  
Pressure Flow ◽  
Darcy Model ◽  
Linear Effects ◽  
Modified Reynolds Equation

The mathematical modeling of aerostatic porous bearings, represented by the Reynolds equation, depends on the assumptions for the flow in the porous medium. One proposes a modified Reynolds equation based on the quadratic Forchheimer assumption, which can be used for both linear and quadratic conditions. Numerical results are compared to those obtained with the linear Darcy model. It is shown that, the non-dimensional parameter Φ, related to non-linear effects, strongly affects the bearing dynamic characteristics, but for values of Φ > 10, the results tend to those obtained with the linear model.

A Review on Active Bearings and Perspectives of Using Them in Rotating Machinery

2014 ◽  
Vol 630 ◽  
pp. 181-187
Author(s):  
Denis Shutin ◽  
Leonid Savin ◽  
Alexander Babin
Keyword(s):  
Mathematical Modeling ◽  
Artificial Intelligence ◽  
Control System ◽  
Motion Control ◽  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
Motion Control System ◽  
Fluid Film Bearings ◽  
System Components

The paper examines the issues of improving the rotor units by means of using support units with actively changeable characteristics. An overview of the known solutions related to the use of active bearings in various types of turbomachinery is provided. A closer look is given at the design and features of active radial bearings, the main elements of which are fluid film bearings. The results of mathematical modeling of active hybrid bearings are presented. The prospects of the use of this type of supports to improve the dynamic characteristics of rotating machinery, including reducing vibrations caused by various factors, are analyzed. Promising directions of development of active bearings are considered, which primarily involves the modification of system components and rotor motion control system algorithms, including intelligent technologies and artificial intelligence methods.

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.

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.

scholarly journals Research of dynamic characteristics of self-propelled railcars methods of mathematical modeling.

2014 ◽  
Vol 2014 (4) ◽  
pp. 16-19
Author(s):  
Дмитрий Гончаров ◽  
Dmitriy Goncharov ◽  
Владимир Кобищанов ◽  
Vladimir Kobishchanov ◽  
Дмитрий Антипин ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Computer Simulation ◽  
Solid State ◽  
Dynamic Characteristics

On the basis of solid-state computer simulation of the motion of self-propelled railcars "North" performed research parameters of its chassis dynamics. Verification of the results performed in-situ sea trials.

Analysis of the Possibilities of the Usage of Electrical Synchronous Link for a CNC Gear Hobbing Machine

2006 ◽  
Vol 113 ◽  
pp. 97-102
Author(s):  
Kastytis Slivinskas ◽  
V. Gičan ◽  
A.J. Poska ◽  
Vytautas Kazimieras Augustaitis
Keyword(s):  
Dynamic Characteristics ◽  
Frequency Characteristics ◽  
Cutting Process ◽  
Dynamical Model ◽  
Mechanical Parts ◽  
The Third ◽  
Gear Hobbing

The method of creating the dynamical model of the CNC gear hobbing machine and for its analyzing is presented in this paper. The model comprises detail mechanical parts of the hob spindle and work spindle axes, their electrical counterparts, linking, and allows one to investigate dynamic characteristics of the machine and to simulate processes, which take place during gear hobbing. The article also presents the simulation diagram, introducing these axes and the third axis, which help to model the cutting process. It also presents results of simulation of processes during hobbing and amplitude-frequency characteristics calculated.

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