Abstract

Designing of an industrial gas turbine rotor needs a special attention to ensure safe and reliable operation of the entire machine. Rotor experiences bending, axial, and torsional vibration during the time of operation and Rotor-stator interaction during whirling involves nonlinearities in the form of friction and impact. Rub-impact is the most common fault in rotating machinery, which causes excessive vibration and reduces the efficiency of the machine. Therefore, it is very important to study and understand the contact phenomena in rotor dynamics. The purpose of this study is to understand the modal interactions that occur in a rotating flexible member. A conceptual test rig for the rotor-stator is developed experimentally and a corresponding numerical model for the system is developed. The test rig consists of a flexible rotor with two discs rotating within a localised conduit. The system is modelled as a Euler Bernoulli beam with two discs. Finite element method is used to model the system. The gyroscopic effects of the rotor also included in the model. The forward whirling frequency obtained from the experiments was used to update the bearing stiffness of the theoretical model. The contact is modelled experimentally using localised conduit with added roughness to aggravate the friction effect. A run-up analysis was carried out within the safe operating regime of the test rig and the frequencies were analysed using a time-frequency plot. The results from the study indicated the possibility of interaction between the forward and backward whirling modes which results in steady nonlinear backward whirl behaviour.

This content is only available via PDF.
You do not currently have access to this content.