Affiliations: Corporate Research & Development Center, Toshiba
Corporation, 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki, 212-8582, Japan
Abstract: This paper describes extensive computer-based analytical studies on
the details of unsteady flow behavior around airfoils subjected to flow induced
vibration in turbo-machinery. To consider the time-dependent motions of
airfoils, a complete Navier-Stokes solver incorporating a moving mesh based on
an analytic solution of motion equation for airfoil translation and rotation
was applied. The drag and lift coefficients for the cases of stationary
airfoils and airfoils subjected to flow induced vibration were examined. From
the numerical results in non-coupling case as out of consideration of the
airfoil motion, it was found that the separation vortex consisted of
large-scale rolls with axes in the span direction, and rib substructures with
axes in the stream direction. In the coupling simulation including the airfoil
motion, both the translation and the rotation displacement were gradually
increased when the airfoil translation and rotation natural frequencies
synchronize exactly with the oscillation frequency of the fluid force. In
addition, the transformation from complex structure with rolls and ribs to
two-dimensional aspect of only rolls could be visualized in three-dimensional
simulation.