Environmental Engineering Reference
In-Depth Information
TABLE 2.1
Relationship between Incoming Wind Speed and Tip Deflection of the Cantilever
Piezoelectric Wind Harvester Beam
Young's
Modulus of
Mylar/Polyethylene
Theoretical
Experimental
v
a
v
b
Force
Terephthalate,
Deflection
Deflection
I (m
4
)
(m/s)
(m/s)
(N)
E
y
(GPa)
(mm)
(mm)
7
1
0.0134
1.29E-14
2.5
6.49
6.5
5
2
0.0059
1.29E-14
2.5
2.84
3.0
3
1
0.0022
1.29E-14
2.5
1.08
1.0
harvester. It can be seen from
Figure 2.32
that there is a measurement ruler
held vertically by a square clamp beside the piezoelectric wind energy har-
vester. The ruler acts like a measurement scale to determine the magnitude
of the deflection at the tip of the harvester, and the neutral/starting point of
the measurement scale has been offset by 9 cm. A silver electric fan is placed
in the background of the four figures to simulate a wind source to the wind
piezoelectric energy harvester. The wind flow generated by the electric fan
excites the harvester to vibrate, and the amount of deflection observed at the
tip of the harvester is read from the measurement ruler.
Figures 2.33
,
2.34
, and
2.35
illustrate the three experiments carried out for incoming wind speeds of
V
a
=7m/s and
V
b
=1m/s,
V
a
=5m/s and
V
b
=2m/s, and
V
a
=3m/s and
V
b
=1m/s, respectively. The experimental deflections read from the three
figures are 6.5 mm, 3 mm, and 1 mm, respectively, and they are recorded in
Table 2.1
to verify the theoretical value of the beam deflection calculated using
9 cm
FIGURE 2.32
Piezoelectric wind energy harvester under no wind speed.
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