It is essential to obtain accurate data during experiments, especially in fluid dynamics.
During this work, one has quantified the flow characteristics in a wind tunnel
behind a cylinder. The measurements were done using a hot-wire anemometer and the
software LABVIEW. The purpose of this experiment is to show how one can understand
physical properties of a flow by acquiring the data oneself.In this experiment, we
have a high Reynolds number. The frequency of the vortex shedding is identified with
the related Strouhal number. Results are also consistent with the Reynolds-Strouhal
relationship for a circular cylinder.The purpose of this work is to measure data from the wake of a cylinder in a wind tunnel. As
we know, the vortex shedding is responsible for the unsteady separation of flow. Depending
on the Reynolds number and the size of the object, the frequency of the vortices can be
found from the velocity measurements. During the experiment, we then measured the
velocity profile in the wind tunnel in order to understand and show physical properties of
the flow. The instantaneous velocity U at one point in turbulent flow can be decomposed
into the mean and the fluctuation: U = U¯ + u
Two different programs were developed on the software LABVIEW: a program that
can measure and write data in a text file, and another which can process the data in
order to quantify flow characteristics. The two programs in LABVIEW allow to choose
the sample rate and the number of samples wanted for the experiment, which means that
one can calculate the mean, standard deviation and the power spectrum of the samples.
Unfortunately, the time we had prevented us to do a lot of measurements, and we could
only repeat the process twice on three distinct points A, B and C and on a line composed
of 16 points, which we will describe in the next section.
In this report, we will first present the experiment and the programs used. Then we will
see the results and discuss them, and we will finish with a conclusion and recommendations
for future work.