Igor Kobzar

Igor Kobzar


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
2 September 2022 in Computation
Verified
Journal Article
Open access
PDF file
OTOleksii Tretiak
Oleksii Tretiak
DKDmitriy Kritskiy
Dmitriy Kritskiy
IKIgor Kobzar
Igor Kobzar
MAMariia Arefieva
Mariia Arefieva
VNViacheslav Nazarenko
Viacheslav Nazarenko
In the presented scientific work, the basic design versions of the thrust bearings of Hydrogenerators are considered. The main causes of emergencies in the thrust bearing unit of a high-power Hydrogenerator are considered. The main requirements for the operation of thrust bearings are submitted. Cause-and-effect relationships of emerging and development of defects are established. Existing methods for calculating the stressed state of a thrust bearing in the classical formulation for a stationary mode of operation are considered. The main features of the operation of the thrust bearing unit are investigated in relation to the features of the sliding bearings. The calculation of the elastic chambers of the hydraulic thrust bearing in a three-dimensional formulation is carried out, taking into account the physical properties of the oil, the material of the chambers and distribution of the acting loads. It is shown that the applied designs of Join Stock Company “Ukrainian Energy Machines” can be used in high-power Hydrogenerators.

16 March 2023 in Computation
Verified
Journal Article
Open access
PDF file
OTOleksii Tretiak
Oleksii Tretiak
DKDmitriy Kritskiy
Dmitriy Kritskiy
IKIgor Kobzar
Igor Kobzar
MAMariia Arefieva
Mariia Arefieva
VSVolodymyr Selevko
Volodymyr Selevko
ITIryna Tretiak
Iryna Tretiak
In this article, the main causes of vibration in the thrust bearing of hydrogenerator motors rated 320 MW are considered. The main types of internal and surface defects that appear on the working surface of the thrust bearing disc during long-term operation are considered. A method of three-dimensional modeling of such defects is presented, and an assessment of the stress-strain state of the heel disc is proposed, taking into account the main forces acting on the working surface using the finite element method. An analysis of the possible further operation of discs with similar defects, in accordance with the technical requirements, is carried out, and we consider ways to eliminate them.

28 October 2022 in Computation
Verified
Journal Article
Open access
PDF file
OTOleksii Tretiak
Oleksii Tretiak
DKDmitriy Kritskiy
Dmitriy Kritskiy
IKIgor Kobzar
Igor Kobzar
VSVictoria Sokolova
Victoria Sokolova
MAMariia Arefieva
Mariia Arefieva
VNViacheslav Nazarenko
Viacheslav Nazarenko
In the submitted scientific work, the existing types of stator fastening design of turbogenerators and the main causes of the stressed state of the stator suspensions are considered. A detailed calculation of the complex stressed state of the turbogenerator stator suspension was carried out for a number of electrical sheet steels, taking into consideration the unevenness of the heat distribution along the horizontal axis of the unit. It is proposed that the calculation of the mechanical stress is carried out by means of the mechanical and thermal calculation, coordinated with the electrical one. The possibility of replacing steel 38Х2Н2ВА with steel 34CrNiMo6 and 40NiCrMo7 is indicated, subject to compliance with GOST 8479-70 for the same strength group.