Mathematical Modelling of Dynamic System Rotor – Groove Seals

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.

ДОСЛІДЖЕННЯ ВЗАЄМОДІЇ РОБОЧИХ ОРГАНІВ БАРАБАНА ВІДЦЕНТРОВОЇ МАШИНИ З ОБРОБЛЮВАНИМ МАТЕРІАЛОМ

Carrying out of analytical research of interaction of operation device of a drum with materials in the centrifugal car for processing of products of the light industry. Determining the dependences and significant parameters of the operation devices that affect the nature of the movement of processed materials in the drum. Methodology. Methods of mathematical study of geometrical parameters of operation devices of the centrifugal machine and their influence on character of movement of the processed material in a hydroextractor drum are used. Results. An analytical study of the interaction of the operation devices of the drum with the material in a centrifugal machine for processing light industry products using methods of mathematical analysis of the geometric shape of the side surface. This method is based on the principle of detecting patterns of motion of material points in the plane of the side surface of the operation device of the drum of the centrifugal machine. The validity of the conclusions of the study on the example of the characteristics of the surface of the operation device of the helical shape is proved. Scientific novelty. The parameters and indicators that must be taken into account when studying the interaction of the operation devices of the drums of centrifugal machines for processing light industry products are analyzed and presented. Practical significance. As a result of the analytical study, the shape was considered and the most significant geometrical parameters of the operation device of the centrifugal machine were determined, which determine the nature of the movement of the processed material in the hydroextractor drum. The obtained dependences and conclusions can be used in the design of the operation devices of centrifugal drum machines for processing various materials in light industry. The information presented in the article is of interest to scientists who study the problems of processing and interaction of materials and mixtures in rotary centrifugal systems, is of practical importance for engineers in mechanical engineering, instrumentation, consumer services, technologists of food, light, chemical and others.

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

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.

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

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.

Research on the influence of workpiece orientation during processing in disc centrifugal machine on the geometrical structure of its surface and processing efficiency

The article describes the result of experiments witch were intended to compare the results of different workpieces orientation in disc centrifugal machine. During experimental investigations, particular attention was paid to the optimal orientation the workpiece in working charge. The results of the research presented in this article confirm the benefit of horizontal orientation of the workpiece to the motion of the media in the working charge.

An Eigensystem Realization Algorithm for Modal Parameter Identification of a Vertical-Shaft High-Speed Centrifugal Machine

In this paper, we utilize the observer/Kalman filter identification (OKID) and the eigensystem realization algorithm (ERA) techniques to identify the modal parameters of a centrifugal machine. To this end, we use an experimental setup to generate a pseudo-impulse input and collect output measurements which are corrupted by noise. We use the pseudo-impulse input and the OKID to find the Markov parameters of the system. Then we form the Hankel matrix of the system and determine the singular values of the system. A minimum-order, state-space model of the system is realized through the Markov parameters and then the natural frequency, damping ratio, mode shapes, and modal amplitudes at the sensor location are estimated by the ERA. We find three models for three separate cases and validate all the three identified models with the measured data and the Waterfall plot. The identified models are useful for designing passive or active vibration suppression control and fault detection systems. The results confirm that OKID/ERA is a reliable time-domain method for identifying the modal parameters of vertical centrifuge machines.

АНАЛІЗ КОЛИВАЛЬНИХ ПРОЦЕСІВ У ВІДЦЕНТРОВІЙ БАРАБАННІЙ ПРАЛЬНІЙ МАШИНІ

Development and analysis of mathematical model of oscillation processes that occur during material processing in centrifugal drum washing machines, determination of absence conditions of contact deformations of working bodies and body of centrifugal machine.