**6. Conclusions**

**5. Wind tunnel construction**

‐2.0 ‐1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

operation.

structure.

ratio, N≈9.

m2

‐2.0 ‐1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

power plant options are presented.

24 Wind Tunnel Designs and Their Diverse Engineering Applications

**5. Wind tunnel construction** 

traditional special purpose single fan.

single fan.

One of the most important points mentioned in this chapter refers to the wind tunnel cost, intending to offer low cost design solutions. Up to now we have mentioned such modifications to the power plant, proposing a multi-fan solution instead of the traditional special purpose

‐7.0 ‐6.0 ‐5.0 ‐4.0 ‐3.0 ‐2.0 ‐1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 Test Section Contraction Settling Chamber Diffuser <sup>1</sup> Corner 1 Corner 4 Diffuser 5 Corner 3 Diffuser 4 Power Plant Diffuser 2 Corner 2 Diffuser 3 fan diameter 1.25 fan diameter 1.25 fan diameter 1.25

Figure 12.Non-dimensional scheme of a wind tunnel with square section test chamber and high contraction ratio, N≈9. Two different standard

One of the most important points mentioned in this chapter refers to the wind tunnel cost, intending to offer low cost design solutions. Up to now we have mentioned such modifications to the power plant, proposing a multi-fan solution instead of the

The second and most important point is the wind tunnel's construction. The most common wind tunnels, including those with square or rectangular test sections, have rounded return circuits, like in the case of the NLR-LSWT. However, the return circuit of DNW wind tunnel is constructed with octagonal sections. Although the second solution is cheaper, in both cases different parts of the circuit needed to be built in factories far away from the wind tunnel location, resulting in very complicated transportation

Figure 13.Non-dimensional scheme of a wind tunnel with rectangular section test chamber and large contraction ratio, N≈9.

‐7.0 ‐6.0 ‐5.0 ‐4.0 ‐3.0 ‐2.0 ‐1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 Test Section Contraction Settling Chamber Diffuser 1 Corner 1 Corner 4 Diffuser 5 Corner 3 Diffuser 4 Power Plant

**Figure 13.** Non-dimensional scheme of a wind tunnel with rectangular section test chamber and large contraction

To reduce the costs, all the walls can be constructed with flat panels, which can be made on site from wood, metal or even concrete, like in the case of ITER's wind tunnel. Figure 14 shows

Both wind tunnels shown in Figure 14 are open circuit. The one on the left is located in the Technological Centre of the UPM in Getafe (Madrid) and its test chamber section is 1,20 x 1,00

used for teaching purposes, although some research projects and students competitions were

. Its main application is mainly research. The right one is located in the Airplane Laboratory

two wind tunnels built with wood panels and aluminium standard profile structure.

of the Aeronautic School of the UPM. Its test chamber section is 0,80 x 1,20 m2

To reduce the costs, all the walls can be constructed with flat panels, which can be made on site from wood, metal or even concrete, like in the case of ITER's wind tunnel. Figure 14 shows two wind tunnels built with wood panels and aluminium standard profile

Both wind tunnels shown in Figure 14 are open circuit. The one on the left is located in the Technological Centre of the UPM in Getafe (Madrid) and its test chamber section is 1,20·1,00 m. Its main application is mainly research. The right one is located in the Airplane Laboratory of the Aeronautic School of the UPM. Its test chamber section is 0,80·1,20 m, and it is normally used for

, and it is normally

The second and most important point is the wind tunnel's construction. The most common wind tunnels, including those with square or rectangular test sections, have rounded return circuits, like in the case of the NLR-LSWT. However, the return circuit of DNW wind tunnel is constructed with octagonal sections. Although the second solution is cheaper, in both cases different parts of the circuit needed to be built in factories far away from the wind tunnel

location, resulting in very complicated transportation operation.

Diffuser 2 Corner 2 Diffuser 3

A method for quick design of low speed and low cost wind tunnels, either for aeronautical and/or civil applications, has been presented.

The possibility of deciding between both applications means that the method allows achieving flow quality level as good as desired.

The method also allows to the designer to get a quick and rough estimation of the overall wind tunnel size, once the main design parameters are given.

The guidelines to choose the secondary design parameters are given as well.

To address the low cost of design and construction, the use of a multi fan power plant and rectangular duct sections is proposed as well.

**Figure 15.** Photographic sequence of the construction of the ITER Low Speed Wind Tunnel. The top left picture shows the foundations, the top right the contraction, the bottom left the power plant and the bottom right a view from the outside almost at the end of the construction.
