Rub-impact behaviors of a multistage bladed drum rotor under high time-varying temperature.

• A rubbing blade-drum model under high time-varying temperature is proposed. • Paroxysmal vibrations caused by sudden temperature rise induce a rubbing fault. • The rub-impact fault is induced or intensified during fluctuating temperature rise. • Reducing a proper exhaust temperature weakens tip-rub and avoids shock vibrations. In a gas turbine, the multistage bladed drum rotor often operates under high time-varying ambient temperature. Thermal deformations of the thin drum could lead to the rub-impact fault between multistage blade rows and the outer casing, which may cause damage to the blades or even the whole machine. Due to the complexity of the thermoelastic coupling solution, rub-impact characteristics of this kind of rotor system are not clear. This study develops a multistage bladed drum rotor model with the rub-impact fault induced by high time-varying temperature. A solution process for the thermoelastic dynamics analysis of the multistage bladed drum rotor system is proposed, combining experimental, numerical, and analytical methods. According to temperature characteristics in a gas turbine, the effect of the high-temperature environment, heating, fluctuating temperature rise, and cooling on the rub-impact fault is the main emphasis of the study. The high-temperature environment could cause a rub-impact fault for the multistage bladed drum rotor. The sudden increase of the exhaust temperature leads to paroxysmal vibrations, which could induce tip rub or make a slight rub-impact fault into a severe accident. Large fluctuation during temperature rise induces the rub-impact fault and even leads to the continuous aggravation of the rub-impact fault. Fortunately, reducing an appropriate exhaust temperature can eliminate or weaken the rub-impact fault and avoid shock vibrations induced by the sudden drop of the high ambient temperature at the same time. Besides, more blade rows could aggravate this kind of rub-impact phenomenon for the multistage bladed drum rotor. Graphical abstract [Display omitted]. [ABSTRACT FROM AUTHOR]