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Calculation of the operational characteristics of the impulse gas-barrier face seal

Kuznetsov Eduard, Pandová Iveta

Management Systems in Production Engineering

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2023

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nr 4 (31)

411--417

EN

The problem of reducing leaks along the pump or compressor shaft of pumped liquids and gases into the environment is very urgent. Serious difficulties have to be faced when sealing the shafts of machines that pump aggressive, toxic, explosive and fire-hazardous environments. According to modern occupational safety requirements, such pumps and compressors should use double seals with a barrier medium whose pressure exceeds the sealed one by 0.05-0.2 MPa. Currently, liquid-lubricated double mechanical seals are widely used in chemical production equipment, however, over the last decade of the 20th century, leading companies have developed a number of designs of double gas mechanical seals for pumps and chemical production devices, which significantly exceed liquid-lubricated seals in their performance characteristics. The vast majority of these seals use a gas-dynamic principle of operation, i.e. spiral, logarithmic, T-shaped or other micro grooves are made on the sealing faces of their rings, which, when rotated, create an additional gas dynamic force that ensures the functioning of these seals with a micron gap between the sealing pair. In this paper, the design, principle of operation and engineering methodology for calculating the main characteristics of a impulse gas barrier face seal, in which one pair of sealing rings performs the functions of a double mechanical seal, is considered. The design is simple, compact and, thanks to the more advanced principle of creating a gap between the sealing pair, is able to maintain operability in a wide range of sealing and barrier pressures. The existing experience of operating seals of this type on chemical production pumps has confirmed their high efficiency, reliability and safety.

2

Rotors of vertical-axial wind turbines assembled in bearings and aerodynamic characteristics of a blade with unclosed wing profile

Panda Anton, Rozhkova Lyudmila, Kuznetsov Eduard, Nahornyi Volodymyr

Management Systems in Production Engineering

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2022

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nr 4 (30)

298--303

EN

In world practice, traditional blades used in high-speed wind turbines, both horizontal-axial and vertical-axial, have a wing-shaped profile. However, for horizontal-axial wind turbines, blades with such a profile have a fairly narrow range of operating values of the angle of attack of the incoming air flow and a low value of the moment of pulling from place. As for vertical-axial wind turbines, the self-starting of the rotor with wing blades is completely absent and additional devices are needed to start the rotor into operation. In order to ensure the selfstarting of the rotor and the operation of the wind turbine at high and low wind speeds, a new shape of the blade profile was developed, called non-closed wing profile. The concept of the development is that the blade should have a configuration in which the pulling force is involved at the beginning of the movement, and then, with the establishing of the movement, a lifting force would arise, which acquires a prevailing character in the operating mode. The article presents the results of experimental studies of the aerodynamic characteristics of the developed non-closed wing blades. One of the results obtained is to determine the effect of the thickness of the blade profile on the range of values of subcritical angles of attack of the incoming air flow and the differences between the nature and range of changes in the coefficients of lifting force and pulling force in a traditional wing blade and a blade with a non-closed wing profile. Studies of the rotor model of a vertical-axial wind turbine with non-closed wing blades have confirmed the presence of its self-starting and operability even at low wind speeds.

3

Blades interaction and non-stationarity of flow in vertical-axial wind turbines

Rozhkova Ludmila, Krenicky Tibor, Kuznetsov Eduard, Nahornyi Volodymyr

Management Systems in Production Engineering

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2021

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nr 4 (29)

280--286

EN

Until recently, horizontal-axial wind turbines with blades having a wing profile occupied a predominant position in the world wind energy market. But currently, vertical-axial wind units are of increasing interest and this is understandable from the point of view of their important features as: no requirements for the orientation of the wind turbine to the wind, the possibility of placing electrical and other equipment on the ground, no requirements for changes of blade chord installation angle along its length. The article discusses the aerodynamics of the vertical-axis wind turbines: the range of changes of angles of incoming flow attack on the blade, the dynamics of changes in the magnitude of the absolute speed of flow of the blade on a circular trajectory of its movement depending on the turbine rapidity, and also obtained in experiments interaction effect of the blades in the rotor. The experiments were carried out on wind turbines with original blades (basic version), which were designed to eliminate the shortcomings of low-speed rotors Savonius (low coefficient of use of wind energy) and high-speed rotors Darrieus (lack of self-start).

4

Gas flow simulation in the working gap of impulse gas-barrier face seal

Kuznetsov Eduard, Nahornyi Volodymyr, Krenický Tibor

Management Systems in Production Engineering

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2020

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nr 4 (28)

298--303

EN

Numerical simulation method of the working process of a centrifugal unit contactless face impulse seal is proposed. A seal functioning physical model was created. Its operation key aspects that are not taken into account in the traditional methods of calculating contactless impulse seals are identified. A numerical simulation of seal working process based on the Reynolds equation solution for the medium vortex-free motion in the gap between moving surfaces is proposed. Hypothesis that simplify the equation's numerical solution for the face impulse seal is formulated. The numerical solution is obtained using the boundary element method. Based on the obtained numerical solution, the distribution of the working medium pressure field in the seal gap is simulated.