KSEF R&D Excellence: Improved Power Generation Via Active Vibration Control of Turbomachinery

Improvement in aerodynamic performance in turbomachinery can significantly enhance power generation efficiency. Turbomachinery involves rotor blades (blades which rotate) and stator vanes (blades which do not rotate). A primary goal in blade design is optimization of aerodynamic performance. Often, however, a blade design optimized for aerodynamic performance is not acceptable because structural analysis predicts large amplitude vibration response, which can result in fatigue failure. So, design modifications are necessary, which may compromise aerodynamic performance. Therefore, it is desirable to develop techniques to control blade vibratory response without significantly altering blade shape. One method involves mounting "smart materials", such as piezoelectric patches, on blades for control actuation to counteract vibrations. A research project at the University of Kentucky is currently underway in which the vibratory response of a stator vane has been reduced significantly in the UK Low Speed Research Compressor using piezoelectric patches. The proposed work would extend this research to develop methods for also minimizing the vibratory response of the rotating blades. There are significant challenges in controlling vibrations of rotating blades. The control is based on feedback of measured response of the vibrating blade. The response is measured through a voltage signal from a sensor, such as an accelerometer. For a stator vane, it is simple to feed wiring ITom sensors to a data acquisition unit. For a rotating blade, however, the sensor signal and control signal must be fed through a slip ring, adding a level of complexity to the system. Verification is needed that this can be accomplished without significant reduction in control effectiveness. It is likely that electrical noise will be introduced by the slip ring. Further, smart materials on a rotating blade will experience centrifugal forces, and best methods for mounting need to be determined to prevent the materials from separating from the blades.