Vibration and stability analysis of steam turbine rotor supported in journal bearings

U ovom radu analiziraju se forme vibriranja i vlastite frekvencije rotora turbine P-7029/17 Tvornice turbina Karlovac. Teoretski dio rada opisuje rotacijske strojeve, njihove dijelove, vrste i postojeće modele. Posebna pozornost pridodana je hidrauličkim ležajevima, koji se opisuju i analiziraju u zasebnom poglavlju. Promatra se uljni film i njegove karakteristike u kliznim ležajevima, kao i sile koje se javljaju radi tlaka u filmu. Analiza samih vibracija i formi vibriranja provodi se za dva slučaja, kada je rotor oslonjen o krute ležajeve i kada je rotor oslonjen o limunske ležajeve. Prvi slučaj se modelira u programu Ansys te se rezultati uspoređuju s rezultatima iz programa Code_Aster. Za drugi slučaj, mjerene vrijednosti koeficijenata ležaja se interpoliraju u Python-u prije same implementacije u Ansys. Tokom modeliranja u programima opisivani su poduzeti koraci. Dobivene forme vibriranja zajedno sa pobudnim frekvencijama prikazane su grafički, dok su ukupni rezultati svih frekvencija i formi prikazani u Campbellovim dijagramima i logaritamskom dekrementu.In this paper, vibration modes, and natural frequencies were analysed for the rotor of P-7029/17 turbine, from Turbine factory Karlovac. The theoretical part of the paper describes rotary machines, their parts, types and existing models. Special attention is drawn to hydraulic bearings which were described and analysed in a separate chapter. The oil film and its characteristics in sliding bearings are observed, as well as the forces that occur due to the pressure in the film. The analysis of the vibrations themselves and the forms of vibration was carried out for two cases, when the rotor is being supported by rigid bearings and when the rotos is supported by sliding bearings. The first case was modelled in Ansys and the results were compared with the results acquired from Code_Aster. In the second case, the measured bearing coefficients values were interpolated using Python before being imported in Ansys. During the modelling, taken steps were described. The obtained forms of vibration along with the excitation frequencies are shown in pictures, while the overview of the results was given with Campbells diagrams and logarithmic decrement