Marysiuk B. Resource characteristics of steam turbines from the action of torsional vibrations

The dissertation is dedicated to the investigation of the influence of torsional vibrations of the shaft arising from abnormal operation modes of the turbogenerator on the resource characteristics of steam turbines. In the introduction, the researcher justifies the state of the research problem under consideration, its relevance, and significance. The purpose and objectives of the scientific investigation are formulated. The scientific novelty and practical significance of the obtained results are indicated. Information regarding the publications and validation of research results is provided, along with the researcher's personal contribution. The structure and scope of the dissertation work are outlined. The first chapter of the dissertation work is dedicated to analyzing literary sources and revealing the current state of research related to the topic of the dissertation. The main factors influencing the fatigue damage of the metal in turbo unit shaft under various operating conditions are analyzed. In the second chapter of the dissertation, an analysis is carried out on the metal damage of the turbine unit rotors resulting from the torsional vibrations of the shaft, which occur during the abnormal mode of operation of the electric generator. The third chapter of the dissertation is devoted to the study of the stress-strain state of the K-200-130 steam turbine shaft during short-circuiting on the turbogenerator. In order to rationalize calculation resources in computer modeling, for the first time, the option of replacing working blades and band fasteners with disks of equivalent length and mass was proposed (the first point of scientific novelty). Torsional vibrations of the turbine shaft resulting from a three-phase short circuit were simulated by applying an additional reactive torque of biharmonic form to the generator rotor.. The magnitude and duration of its action are random variables. The tangential stresses were calculated with a surge duration of 0,02 s. The second point of scientific novelty is formulated. In the fourth chapter, the stress-strain state of the shaft of the K 1000 60/3000 turbo unit is investigated under abnormal operating conditions of the electric generator. Based on the obtained stress-strain state of the shaft, the impact of torsional vibrations of the turbo unit shaft on its resource characteristics has been assessed. The third point of scientific novelty has been formulated: the stress-strain state calculation model and residual resource estimation for the turbine shaft of the K-1000-60/3000 turbo installation have been enhanced to investigate the impact of torsional vibrations. The fourth point of scientific novelty was formulated: for the first time, a comparative assessment of shaft metal damage due to torsional vibrations occurring when the turbogenerator is connected to the power system with rough synchronization was carried out for a project shaft and a shaft after restoration (without one operating stage). In the fifth chapter of the dissertation, the results of the investigation into the thermal and stress-strain state of the high-pressure cylinder rotor after damage are presented for both nominal and startup modes of power unit operation. This research was performed at the Department of Thermal and Alternative Energy by the applicant in co-authorship.