During the design process of the new boundary layer wind tunnel, the recommendations of the international literature, the experience of current and former colleagues of the Department of Fluid Mechanics and the opinions of multiple foreign experts were all taken into account.
According to these, the width of the wind tunnel test section has to be at least approximately 3 m wide. The so-called boundary layer generating section, where the roughness elements placed on the ground create a flow similar to the atmospheric boundary layer, should be at least 10 m long. This ensures that the gustiness of the created air flow and the size of the vortices are realistic on the planned model scale of 1:200.
The experience of personal visits to several wind tunnel laboratories abroad (University of Surrey, ETH Zürich /EMPA, KIT Karlsruhe, Universität Hamburg, TU Eindhoven) also had an effect on the design process. The specifications of wind tunnels which were constructed for building- and environmental aerodynamics measurements have been recently summarized.
Based on the available literature, there are two wind tunnel configurations that seem to ensure the maximum range of applications:
- An open-circuit wind tunnel which uses the air inside the laboratory, but is also able to use external air due to optional openings on the laboratory walls (e.g. in case the tracer gas emitted in dispersion experiments needs to be cleared from the laboratory)
- A recirculating wind tunnel, in which the recirculated air can be changed again optionally, through openings.
Due to the available space in the building and the lower construction costs, we have chosen the first possibility. The planned layout of the wind tunnel is shown on the images below.
- Test section size: 15 – 17 x 3 x 2 m
- Full length: approx. 26 m
- Maximum wind speed: 20-25 m/s
- Fan power: 6 x 30 or 6 x 37 kW
During the design process, we will rely on our experience from the smaller wind tunnels designed at the Department of Fluid Mechanics, the solutions at the Gödöllő wind tunnel which was designed under the leadership of Dr. János Vad, and the construction methods seen in wind tunnels abroad, from which examples are shown below.