Aerodynamic Cross-coupling in a Flexible Rotor: Control Design and Implementation

This paper is concerned with modeling and active vibration control of a 1.23-m long flexible shaft on active magnetic bearings that is designed to model a small industrial compressor and to serve as a platform for investigating emerging control schemes. Aerodynamic cross-coupled stiffness is one of the main contributors to rotordynamic instability in modern turbo-machines. The destabilizing effects of the cross-coupled stiffness are demonstrated. H2 and H∞ synthesis approaches are used to design controllers that may stabilize the rotor-bearing system over a wide range of cross-coupled stiffness. Stability analysis and dynamic simulations of the resulting closed-loop systems are performed and recommendations made on the best means of achieving the desired performance and stability of the rotor-bearing system. The control and data-acquisition are in the process of being implemented in real-time using a DSP system.