Active Balancing of Turbomachinery: Application to Large Shaft Lines

Abstract

Unbalance defects are inherent to rotating machinery manufacturing and cause important vibra tions that are necessary to decrease. This work, which comes after a bibliographical study, relates to active balancing of rotors. The unbalance correction is carried out in real time, during operation in steady state and transient responses. The concept suggested consists of generating a correction force using two mobile weights situated in the same plane and running at a constant radius of the rotation axis. The balancing process is based on the influence coefficients method and includes specific measurement and control developments. Influence coefficients are determined in a first step and then used to balance the rotor at a specified speed during its transient response to minimize vibrations at critical speeds. A first experimental application is presented. A technological device designed for large-sized machines is described and used to balance a single rotor test bench. The technology and the process efficiencies are shown: vibrations at critical speed are strongly de creased. A simulation of active balancing of the rotor is then carried out to validate the simulation's procedure compared to experimental results. The second application is a numerical simulation of the active balancing of an industrial turbogenerator group passing through multiple critical speeds. Results show the active balancing of a multirotor machine's advantage compared to conventional balancing.