Abstract:
|
This report aims to contribute to the knowledge and characterization of grid generated
turbulence in a wind tunnel. It starts with a theory introduction to turbulence
where we bring together the classic approaches (Richardson-Kolmogorov
equilibrium cascade) and more recent research. The latter includes the nonequilibrium
dissipation law developed by [Valente and Vassilicos, 2011] and calculus
methods such as set forth by [Puga and LaRue, 2017]. The study is based on two
grids: an active grid in two different modes (open and random) and a regular
and irregular passive grids.
In terms of the means employed, the data is gathered using a hot-wire
anemometer which makes it possible to have a high time resolution even though
only one point and 1D turbulence is collected. In addition, the software used in
the mathematical processing is MATLAB.
The crucial parameters analyzed are the variations, the lengthscales (as
well as their interaction) and dissipation rate constants, both equilibrium and
nonequilibrium definitions. Some significant results have been found. In the first
place Kolmogorov hypotheses are justified to hold true. Furthermore, there are
some signs that the nonequilibrium law seems a plausible answer to some instabilities
perceived. Finally, the vertical profiles of the irregular grid clearly show
that the turbulence generated is inhomogeneous, which ushers in new lines of
investigation. |