**4. Outline of wind tunnel configuration**

These tests were aimed at measuring local wind pressure on the horn-shaped membrane roof using the Eiffel type wind tunnel as shown in table 1 and figure 5. The turbulent boundary layer flow was made by the roughness blocks, the spires and the trips (show in figure 6). The *P <sup>j</sup> -P <sup>s</sup>*, which *P <sup>j</sup>* is the pressure at the measurement pressure tap *j* and *P <sup>s</sup>* is the static pressure at the pitot tube, was measured directly by the laboratory pressure transducer as a differential pressure and represents the wind pressure acting at the particular pressure tap location *j* within the computer as sown in figure 7.


**Table 1.** Outline of wind tunnel configuration

**Figure 5.** Sketch of Eiffel wind tunnel used

Wind Tunnel Tests on Horn-Shaped Membrane Roof Under the Turbulent Boundary Layer http://dx.doi.org/10.5772/54180 131

**Figure 6.** Cross-section diagram of wind tunnel facilities

**4. Outline of wind tunnel configuration**

130 Wind Tunnel Designs and Their Diverse Engineering Applications

Wind tunnel facility Eiffel type wind tunnel

Length of wind tunnel 31000mm

Form GFPR's axial fan Wing shape φ=2500mm Volume About 100

Contraction ratio 1 : 3 Velocity range 0.0~25.0

the computer as sown in figure 7.

**Table 1.** Outline of wind tunnel configuration

**Figure 5.** Sketch of Eiffel wind tunnel used

Wind tunnel

Blower

These tests were aimed at measuring local wind pressure on the horn-shaped membrane roof using the Eiffel type wind tunnel as shown in table 1 and figure 5. The turbulent boundary layer flow was made by the roughness blocks, the spires and the trips (show in figure 6). The *P <sup>j</sup> -P <sup>s</sup>*, which *P <sup>j</sup>* is the pressure at the measurement pressure tap *j* and *P <sup>s</sup>* is the static pressure at the pitot tube, was measured directly by the laboratory pressure transducer as a differential pressure and represents the wind pressure acting at the particular pressure tap location *j* within

Section size 2200×1800×17300mm (width×height×length)

**Figure 7.** The wind pressure acting at the particular pressure tap location *j*

#### **5. Outline of the turbulent boundary layer flow**

In this chapter, the outline of the turbulent boundary layer flow is described. Table 2 shows conditions and parameters on the tests. It was assumed that a model scale was 1: 100 and that a velocity scale was 7/27 at the full scale wind speed 34m/s. In this case, time scale was 11/125, and additional flow conditions indicate in figure 9. Airflow conditions which were the average wind speed profile, the turbulence intensity, the power spectral density of fluctuating wind speed and the scale of turbulence for this test, are shown in figure 9. The velocity gradient *α* was 0.2 and the turbulent intensity around the roof was about 0.3. This wind was simulated natural wind in the urban area, namely "terrain 3" in the Building Standard Low of Japan.

#### **Figure 8.** Photos of wind tunnel test


#### **Table 2.** Airflow Condition on the wind tunnel


**Table 3.** Model Condition

Wind Tunnel Tests on Horn-Shaped Membrane Roof Under the Turbulent Boundary Layer http://dx.doi.org/10.5772/54180 133

**Figure 9.** Wind flow conditions in the wind tunnel test

**boundary layer flow** 

**6.1 Outline of tests** 

Fig. 9, Wind flow conditions in the wind test

#### This chapter focuses on the stand-alone model of horn-shaped membrane roof and indicates wind pressure and fluctuating pressure around models under the boundary turbulent layer flow which was shown in the preceding section. **6. The wind tunnel test on the stand-alone model under the turbulent boundary layer flow**

The 100mm x 100mm square based model was used in this test. Major parameters were three types of rise-span ratio (h/L), namely h/L=0.1, 0.2 and 0.3, and the presence of walls. Six types of model were prepared for this wind tunnel test. The outline of models and measurement taps show in figure 10 and figure 11. This chapter focuses on the stand-alone model of horn-shaped membrane roof and indicates wind pressure and fluctuating pressure around models under the boundary turbulent layer flow which was shown in the preceding section.

These models were made from acrylic plastic. As for the open type model, the roof depth

**6. The wind tunnel test on the stand-alone model under the turbulent** 

#### was about 5mm in order to measure both sides of the roof at the same time (show in figure 12). Additionally, wind directions were only four types which were 0-deg., 15-deg., 30-deg. **6.1. Outline of tests**

speed and the scale of turbulence for this test, are shown in figure 9. The velocity gradient *α* was 0.2 and the turbulent intensity around the roof was about 0.3. This wind was simulated natural wind in the urban area, namely "terrain 3" in the Building Standard Low of Japan.

Boundary Turbulent Layer Flow

Terrain 3 in The Building Standard Law of Japan)

(Urban Area;

Wind velocity About 7 m/s at z=35mm (around the test model)

Velocity turblence intensity Ir 0.3 at z=35mm (around the test model)

Model Type Stand-alone model, Multi-bay Model

Model scale 100mm x100mm ( model : full =1:100)

Wind direction 0-degree, 15-degree, 30-degree, 45-degree

Wall Open type / Enclosed type

**Figure 8.** Photos of wind tunnel test

132 Wind Tunnel Designs and Their Diverse Engineering Applications

Velocity gradient α α=0.2

**Table 2.** Airflow Condition on the wind tunnel

Sampling speed 500Hz Sampling time 30sec

Rise-span ratio h/L 0.1, 0.2, 0.3

Number of test on each model Five times

**Table 3.** Model Condition

Flow

and 45-deg., because of symmetry form of roof. The 100mm x 100mm square based model was used in this test. Major parameters were three types of rise-span ratio (h/L), namely h/L=0.1, 0.2 and 0.3, and the presence of walls. Six types of model were prepared for this wind tunnel test. The outline of models and measurement taps show in figure 10 and figure 11.

These models were made from acrylic plastic. As for the open type model, the roof depth was about 5mm in order to measure both sides of the roof at the same time (show in figure 12). Additionally, wind directions were only four types which were 0-deg., 15-deg., 30-deg. and 45-deg., because of symmetry form of roof.

**Figure 10.** Experimental models and measuring points on the stand-alone models; two types model was prepared, namely "Open type" and "Enclosed type"

**Figure 11.** The photo of models; three types of h/L models which was made from acrylic plastic. The depth of open type's roof is about 5mm thick.

**Figure 12.** Details of the experimental model

#### **6.2. Results of mean wind pressure coefficient on the stand-alone model**

Distributions of mean wind pressure coefficient on each model are indicated in figure 13 and 14. The distribution of wind pressure coefficient changed the value depending on the presence of the wall. Similarly, the wind pressure coefficient distributions depended on the wind direction.

In the open type, the negative pressure concentrated at the windward side on the model. On the other hand, the negative pressure observed at the top of the roof on the enclosed model. Moreover, the negative pressure around the top of roof was increase with increasing of a risespan ratio.

**Figure 10.** Experimental models and measuring points on the stand-alone models; two types model was prepared,

**Figure 11.** The photo of models; three types of h/L models which was made from acrylic plastic. The depth of open

**6.2. Results of mean wind pressure coefficient on the stand-alone model**

Distributions of mean wind pressure coefficient on each model are indicated in figure 13 and 14. The distribution of wind pressure coefficient changed the value depending on the presence of the wall. Similarly, the wind pressure coefficient distributions depended on the wind

h/L=0.3

h/L=0.2

h/L=0.1

namely "Open type" and "Enclosed type"

134 Wind Tunnel Designs and Their Diverse Engineering Applications

type's roof is about 5mm thick.

**Figure 12.** Details of the experimental model

direction.

Enclosed type Open type

**Figure 13.** Mean wind pressure coefficient which was obtained from wind tunnel tests on enclosed type of the standalone mode

**Figure 14.** Mean wind pressure coefficient which was obtained from wind tunnel tests on open type of the standalone mode

#### **6.3. Results of fluctuating wind pressure coefficient on the stand-alone model**

This section shows the distributions of fluctuating wind pressure coefficient on each model (show in figure 15 and 16). The fluctuating wind pressure coefficient Cf ' was obtained from the following equations;

$$\mathbf{C}\prime = \frac{\sigma\_p}{q\_z} \tag{9}$$

in which σp is fluctuating wind pressure at pressure tap p on the model and *q*¯ *<sup>z</sup>* is the mean value of dynamic velocity pressure at the reference location. The maximum value of the fluctuating wind pressure is "1.0" and the minimum value of the fluctuating wind pressure is "0".

Thetestresult showedthattheCf 'oftheenclosedtypesweredifferentdistributionfromtheopen types. Furthermore the Cf ' of the enclosed type was larger than that of the open type. Especial‐ ly,themodeltypeh/L=0.2oftheenclosedmodel showed0.75aroundthe centerofthe roof.These results may cause some effects on the response of membrane, since the membrane structure is generally sensitive structure for the external force such as wind load with turbulence.

**Figure 15.** Fluctuating wind pressure coefficient which was obtained from wind tunnel tests on enclosed type of the stand-alone mode

#### **6.4. Results of peak wind pressure coefficient on the stand-alone model**

Distributions of the peak wind pressure coefficient on each model are indicated in figure 17 and 18. Generally, the peak wind pressures around corner of roof distinct from distributions Wind Tunnel Tests on Horn-Shaped Membrane Roof Under the Turbulent Boundary Layer http://dx.doi.org/10.5772/54180 137

**6.3. Results of fluctuating wind pressure coefficient on the stand-alone model**

' *<sup>p</sup> <sup>f</sup> z*

wind pressure is "1.0" and the minimum value of the fluctuating wind pressure is "0".

generally sensitive structure for the external force such as wind load with turbulence.

*q* s

in which σp is fluctuating wind pressure at pressure tap p on the model and *q*¯ *<sup>z</sup>* is the mean value of dynamic velocity pressure at the reference location. The maximum value of the fluctuating

ly,themodeltypeh/L=0.2oftheenclosedmodel showed0.75aroundthe centerofthe roof.These results may cause some effects on the response of membrane, since the membrane structure is

**Figure 15.** Fluctuating wind pressure coefficient which was obtained from wind tunnel tests on enclosed type of the

Distributions of the peak wind pressure coefficient on each model are indicated in figure 17 and 18. Generally, the peak wind pressures around corner of roof distinct from distributions

**6.4. Results of peak wind pressure coefficient on the stand-alone model**

*C*

(show in figure 15 and 16). The fluctuating wind pressure coefficient Cf

the following equations;

136 Wind Tunnel Designs and Their Diverse Engineering Applications

Thetestresult showedthattheCf

types. Furthermore the Cf

stand-alone mode

This section shows the distributions of fluctuating wind pressure coefficient on each model

' was obtained from

= (9)

'oftheenclosedtypesweredifferentdistributionfromtheopen

' of the enclosed type was larger than that of the open type. Especial‐

**Figure 16.** Fluctuating wind pressure coefficient which was obtained from wind tunnel tests on open type of the stand-alone mode

of the internal area. However, this test showed that peak wind pressure coefficients around the middle of roof (i.e. the top of roof) were the maximum negative value. In addition, the peak wind pressure coefficient of the enclosed model was larger than that of the open type. For example, focusing on the enclosed model, the model of h/L=0.2 and 0.3 show more than -4.0. Furthermore, the distribution varied according to the parameter of wind direction and risespan ratio.


**Figure 17.** Peak wind pressure coefficient which was obtained from wind tunnel tests on enclosed type of the standalone mode


**Figure 18.** Peak wind pressure coefficient which was obtained from wind tunnel tests on open type of the standalone mode
