AN IMPROVED ROTOR MODEL WITH EQUIVALENT DYNAMIC EFFECTS OF THE SUPPORT STRUCTURE

Abstract

Dynamic effects of the support structure are important in vibration analyses of a rotor. It may well happen in real machines such as centrifugal pumps or turbines operating on a flexible structure. This paper suggests an improved rotor model for including the support effects efficiently into the rotor-bearing system. The support FRFs are used to extract the spring–mass models which have the same dynamic characteristics of the support structure. These regenerated models are directly inserted into the rotor. On the other hand, the impedance coupling method, which is often used in structural vibration problems, is presented to verify the suggested modelling technique. It is based on the FRFs of each substructure and the constraint conditions of interface co-ordinates. To demonstrate the applicability and validity of the analytical procedures, they are applied to the rotor of a double suction centrifugal pump. As a result, they show a good agreement with each other.