Serhii Shevchenko
G.E. Pukhov Institute for Modelling in Energy Engineering, United Productions Ltd.
Abstract Title:Sealing Systems and their influence on Rotor Dynamics
Biography:
Serhii Shevchenko was born in 1961, graduated from the Kharkiv Polytechnic Institute (KhPI) in 1984 (specialty: "Hydraulic machines and means of automation"). In 1990, he defended his Ph. D thesis on the topic "Development and research of new designs of stuffing-box seals for NPP pumping equipment." He worked at the research laboratory of machines’ vibration reliability at the theoretical mechanic's department of the Sumy branch of KhPI (later Sumy State University): as a research associate from 1984 to 1994 (as a junior researcher since 1986, as senior researcher since 1991), participated in the development for the Aircraft technology and NPP. Since July 2020, he has been a senior researcher at the G.E. Pukhov Institute for Modelling in Energy Engineering of National Academy of Sciences of Ukraine (IPME). In June 2023, he defended his doctoral (Doctor of Engineering) thesis on the topic "Mathematical models of processes in the sealing systems of centrifugal machines". The area of S. Shevchenko's research related to the methods development of sealing theory and vibration reliability of centrifugal machines.
Research Interest:
In liquid rocket engines, the fuel supply system is implemented by turbopump units, which include pumps and a pump drive - a gas turbine. Turbopump units supply highly aggressive and toxic fuel components to the combustion chamber, which can enter into a chemical reaction when interacting. The physical properties of the working fluids supplied by the pumps and the working fluid in the gas turbine tract differ significantly. Therefore, it is very important to ensure the sealing of the unit cavities with different pressures, as well as to prevent the leakage of aggressive liquids to the outside. Design measures aimed at increasing the hydraulic resistance of seals, as a rule, increase their hydrostatic rigidity and damping, and thereby improve their dynamic qualities. Thus, non-contact seals, in addition to sealing, perform an equally important function - they improve the vibration state of the centrifugal machine. Dynamic characteristics are especially important for seals in high-speed rotary machines. The studies have shown that all sealing units with throttling gaps or sealing paths filled with a high-pressure sealed medium should be considered as dynamic systems. The sealed medium affects the dynamic state of the rotor, acting on the walls of the sealing paths. The greater the hydraulic resistance we create in the sealing gaps (for example, due to taper), the more energy is spent on overcoming these channels by the sealed medium, the more the sealing units dynamically reinforce the rotor, improving its vibration characteristics. It is shown that a targeted selection of seal design parameters allows improving the vibration state of the rotor. An initially dynamically "flexible" rotor in combination with correctly designed seals can become dynamically "rigid". Based on the study of the hydromechanical model of a gap seal and models of rotors in gap seals, analytical dependencies were obtained that describe the radial-angular oscillations of the rotor. Methods for calculating and designing sealing systems are proposed that take into account oscillatory processes caused by the hydrodynamic characteristics of the seals.