pool, driving device, wave energy conversion device (gas chamber and turbine
generator set), sensor and data acquisition system.
Referring to Fig. 14.9, the dynamic coordinate system fixed on the wave energy
device is taken. The transport motion h 0 is the relative water level of the still pool.
Assuming that the flow in the air chamber is a quasi-steady one-dimensional flow,
the oscillating water column can be regarded as a rigid body with variable length
and heave motion. According to the principle of fluid mechanics, the as follows.
€ h i À € h 0
À
Á
L þ DL þ h i
ð
Þ þ
Dp
c x
þ h i À h 0
g þ
b
q x F a
h i À h 0
ð
Þ¼0
ð14:24Þ
where,
DL Additional mass term of oscillating water column, called “additional water
column length”;
b
Heave damping.
When the air chamber has symmetrical wing, the pressure difference between the
inside and outside of the air chamber is the sum of the pressure drop of the turbine
unit and the dynamic pressure loss of the turbine outlet. There is
Exhaust process
Dp ¼
1
2
q V
3
t þ C v S x
2 r
2
þ V
2
t
À
Á
Â
Ã
ð14:25Þ
Inspiratory process
Dp ¼ À
1
2
q V
3
t þ C v S x
2 r
2
þ V
3
t
À
Á
Â
Ã
ð14:25’Þ
When there is a nozzle in the air chamber (considering the ideal nozzle), the
pressure difference between the inside and outside of the air chamber is the dynamic
pressure at the nozzle outlet. There is
Exhaust process
Dp ¼
1
2
qV
3
t
ð14:26Þ
Inspiratory process
Dp ¼ À
1
2
qV
3
t
ð14:26’Þ
where
366
14 Pneumatic Principle and Device of Oscillating Water …