wave is close to the natural frequency, the system will produce resonance, thus
increasing the amplitude of the water column in the air chamber. When the oscillator is in resonance state, the combined action of incident wave and radiation wave
increases the wave height in the direction of incident wave, while the wave height
in the back of the oscillator decreases, thus increasing the efficiency of wave energy
conversion device. The greatest advantage of oscillating water column device is
The relatively fragile mechanical parts, such as turbines, are only in contact with
reciprocating air and not with waves. Therefore, they have better performance and
lower failure rate than direct wave energy conversion devices which are in direct
contact with waves in resisting severe weather. But its shortcomings are also
obvious, mainly as follows: (1) The construction cost is expensive; (2) The conversion efficiency is low, and the total efficiency of converting wave energy into
electricity is 10–30%.
Wave energy devices of oscillating water column can be divided into two types:
floating type and fixed type. At present, air is used as the medium of conversion in
the wave energy devices of oscillating water column. The first energy conversion
mechanism is air chamber, and the second energy conversion mechanism is air
turbine. The lower opening of the air chamber is connected with seawater underwater, and the upper opening of the air chamber is connected with the atmosphere,
namely, the nozzle. Under the action of wave force, the water column at the bottom
of the chamber vibrates in the chamber. The air in the compressed chamber passes
through the nozzle to and fro, and the wave energy is converted into the pressure
energy and kinetic energy of the air. An air turbine is installed at the nozzle and the
turbine shaft is connected with the generator, compressed air can be used to drive
the turbine to rotate and drive the generator to generate electricity.
14.3 Mathematical Model of Oscillating Water Column
Taking the Japanese “Mighty Whale “ as an example, the mathematical model of
oscillating water column wave power generation device is calculated. Figure 14.5
shows a typical floating oscillating water column wave generator (OWC, Mighty
Whale, 110 kW). “Mighty Whale” is the latest offshore wave power generation test
platform developed by Japan Marine Science and Technology Center after
“Kaimei” in the 1970s and 1980s. The basic principle of wave energy power
generation is the same as that of “Kaimei”. It uses the oscillating water column
generated by the wave entering the air chamber to drive the turbogenerator to work.
There is an opening in the direction of incident wave, and there are three air
chambers in the opening. The figure shows a cross section of the air chamber.
Horizontal vibration generates an interactive airflow, whose gas energy drives the
vane motor to rotate. The size of Mighty Whale energy converter is shown in
Fig. 14.6. The frequency response method is used here to make some simple
introductions.
14.2 Basic Structure and Pneumatic Principle
355
increasing the amplitude of the water column in the air chamber. When the oscillator is in resonance state, the combined action of incident wave and radiation wave
increases the wave height in the direction of incident wave, while the wave height
in the back of the oscillator decreases, thus increasing the efficiency of wave energy
conversion device. The greatest advantage of oscillating water column device is
The relatively fragile mechanical parts, such as turbines, are only in contact with
reciprocating air and not with waves. Therefore, they have better performance and
lower failure rate than direct wave energy conversion devices which are in direct
contact with waves in resisting severe weather. But its shortcomings are also
obvious, mainly as follows: (1) The construction cost is expensive; (2) The conversion efficiency is low, and the total efficiency of converting wave energy into
electricity is 10–30%.
Wave energy devices of oscillating water column can be divided into two types:
floating type and fixed type. At present, air is used as the medium of conversion in
the wave energy devices of oscillating water column. The first energy conversion
mechanism is air chamber, and the second energy conversion mechanism is air
turbine. The lower opening of the air chamber is connected with seawater underwater, and the upper opening of the air chamber is connected with the atmosphere,
namely, the nozzle. Under the action of wave force, the water column at the bottom
of the chamber vibrates in the chamber. The air in the compressed chamber passes
through the nozzle to and fro, and the wave energy is converted into the pressure
energy and kinetic energy of the air. An air turbine is installed at the nozzle and the
turbine shaft is connected with the generator, compressed air can be used to drive
the turbine to rotate and drive the generator to generate electricity.
14.3 Mathematical Model of Oscillating Water Column
Taking the Japanese “Mighty Whale “ as an example, the mathematical model of
oscillating water column wave power generation device is calculated. Figure 14.5
shows a typical floating oscillating water column wave generator (OWC, Mighty
Whale, 110 kW). “Mighty Whale” is the latest offshore wave power generation test
platform developed by Japan Marine Science and Technology Center after
“Kaimei” in the 1970s and 1980s. The basic principle of wave energy power
generation is the same as that of “Kaimei”. It uses the oscillating water column
generated by the wave entering the air chamber to drive the turbogenerator to work.
There is an opening in the direction of incident wave, and there are three air
chambers in the opening. The figure shows a cross section of the air chamber.
Horizontal vibration generates an interactive airflow, whose gas energy drives the
vane motor to rotate. The size of Mighty Whale energy converter is shown in
Fig. 14.6. The frequency response method is used here to make some simple
introductions.
14.2 Basic Structure and Pneumatic Principle
355