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8.
9.
LINFLOW creates an “laullf.rls” in the end of the run, in which the fluidelastic eigenvalues and eigenvectors are stored. To view the eigenvector in
LINFLOW type the “show aerelas vg” command in the LINFLOW window as
shown above and hit the “Enter” key on the computer keyboard. This will
produce the output shown below.
The results shows that the first eigenvector has converged to about 29.18 Hz
and that the damping requirement for neutral stability is -0.02472 (this means
that the mode has fluid-elastic damping ratio of about 2.47% (this is sometimes
called acoustic radiation damping when flow field is at rest). The velocity index
V is almost equal to the user specified small velocity, which is an indication of
that the converged mode.
NOTE, If a converge mode damping requirement is positive, this indicates that
the mode picks up energy from the fluid dynamic if executed (hence, negative
type of damping contribution destabilising the fluid-elastic mode)