"Detection, tracking and analysis of turbulent spots
and other coherent structures in unsteady transition"
by
Lewalle, J.
ABSTRACT
Transition on turbine blades is an important factor in the
determination of eventual flow separation and engine performance.
The phenomenon is strongly affected by unsteady flow conditions
(wake passing). It is likely that some physics of unsteadiness
should be included in advanced models, but it is unclear which
properties would best embody this information. In this paper,
we use a GEAE experimental database in unsteady transition
to test some tools of spot identification, tracking and
characterization. In this preliminary study, we identify
some parameters that appear to be insensitive to wake passing
effects, such as convection speed, and others more likely to
require unsteady modeling.
The main findings are that wavelet duration can be used as
a measure of spot size, and that spot energy density is most
closely correlated to the wake passing. The energy density
is also correlated to spot size, but spot size appears
unrelated to the phase angle.
Recommendations are made for further study.
submitted, NASA-CR, 2000.
Jacques Lewalle, jlewalle@syr.edu
