BLADE VIBRATION MEASUREMENTS AND EXCITATION FORCE EVALUATION
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Turbomachinery Laboratory, Texas A&M Engineering Experiment Station
Abstract
Tip timing blade vibration measuring systems have
become nowadays common for monitoring blade vibrations,
due to rather easy and non-intrusive installation of sensors. The
data collected by the sensors must be heavily processed in order
to get the vibration time histories of all blades at rated speed or
during a run up or run down transient. In the paper a real case
of tip timing measurement for a steam turbine is shown.
Resonant/natural frequencies, amplitude and phase of each
blade vibration with respect to the synchronous reference, are
identified. The first measurement results shown are related to
asynchronous vibrations of a steam turbine last stage blade row
due to an instability. The second results are instead transient
synchronous vibrations when passing a blade row resonance
during a run up of the steam turbine. It is further shown how
synchronous vibrations, although non stationary, allowed to
identify damping and excitation amplitudes by means of an
original approach based on modal analysis.
Description
Lecture