Abstract
Turbomachineries are generally high-energy systems operating at supercritical speeds. Often, nonlinear effects and latent instabilities are encountered during its operation which significantly influence the synchronous and asynchronous response of the rotor. The cause may be fluid film bearing, seal rubs, shaft joints and couplings, varied acceleration rates. Accordingly one may have a varied response behavior viz. Sub and super-harmonic oscillations, jump phenomenon, limit cycles, etc. The development phase of an aero gas turbine engine faces such challenges and these problems have to be addressed to achieve a flight-worthy engine.
The present paper discusses two case studies encountered during the development phase of an aero-engine in detail. First, is a case study of self-excited vibration caused due to oil inadvertently trapped in the internal cavity of hollow rotor and second, is the case demonstrating jump phenomena in case of a shaft with diaphragm couplings. The results acquired are well corroborated with the feedback and benchmarks. Wherever necessary, theoretical modeling has been resorted to validate the findings and get a better insight into the problem.
