Progress in research and application of oscillating water column wave power generation devices

2.3 Numerical Simulation

With the development of computer technology, numerical simulation method has been widely used by researchers. Many scholars use computational fluid dynamics (CFD) to simulate it numerically. The traditional method is mainly based on the combination of digital-model-physical model system. Paixao et al. [19] studied a typical OWC structure by numerical simulation, verified it by physical model, obtained the influence of water mist on the turbine, and reduced the damage of water mist by changing the turbine front structure. Luo et al. [20] established a CFD numerical model, studied the conversion efficiency of fixed OWC wave power generation device under nonlinear conditions, and obtained the optimal gas chamber attenuation coefficient. Nader et al. [21] established a numerical model based on the finite element theory, studied the gas chamber arrangement of multi-chamber OWC, and came up with a more effective arrangement.

With the emergence of commercial software, more and more scholars are attracted by its strong stability and reliability, and many scholars have changed from the traditional method of combining digital analog with physical analog to the method of combining digital analog with commercial software, physical analog with commercial software or commercial software with commercial software. Teixeira et al. [22] established a numerical model based on N-S equation, studied the free surface pressure of water body in OWC gas chamber, calculated and compared it with FLUENT, a commercial fluid mechanics software, and finally proposed an optimization method for the structure. Bouali et al. [23] established numerical wave flume and numerical model based on ANSYS-ICEMCFD software and CFX software respectively, studied the influence of OWC chamber structure and size on wave energy conversion under second-order Stokes wave conditions, and proposed optimization methods. Compared with physical model test, numerical simulation has low cost, convenient operation and strong repeatability, which brings great convenience to the structural optimization design of OWC.

Application progress of 3OWC wave power generation device

In the continuous research and exploration of human beings, the OWC wave energy conversion device has experienced the development from miniaturization to large-scale, and has gradually crossed from offshore to deep sea. Despite the difficulties and many failures, there are still many successful cases that represent the application progress of OWC wave power generation devices.

3.1 Application progress of OWC devices abroad

(1) Small OWC device. The earliest recorded use of the OWC was the 19th-century whistling buoy, a successor to the bell buoy, which navigated by sound. According to Scientific American in 1885, 34 of these devices were deployed along the East coast of the United States. [25]

In 1910, the Frenchman Praceique-Bochaux used the pump principle to build a small wave power device to supply electricity to his beachfront house. [26] In 1940, Masuda Shinao, the father of wave power generation, proposed the OWC structure for the first time and successfully used it in navigation lights [27]. Figure 2 shows Uraga beacon light produced on the basis of OWC principle at that time, whose cost and stability reached the commercial standard [28]. The device is also equipped with self-protection devices and charge and discharge pool, and when the generated electricity exceeds the consumption, it is stored in the battery for emergency needs. Although these devices are only rated at 60 W, which can only meet the electricity demand of a beacon light, they are the first wave power equipment to be commercialized.

(2) Large onshore OWC device. In 1991, Wavegen, in conjunction with Queen's University of Northern Ireland, installed a 75 kW single-unit wave power plant on the island of Islay. [29] The unit was connected to the grid between 1991 and 2000, and after decommissioning the turbine was placed in the Deutsches Museum in Munich. At the same time, two OWC prototype power stations were established in Asia: the 60 kW OWC Shore Wave power Station at Sakata Port in Japan [30] and the 125 kW wave power station at Trivandrum Port in India [31]. Based on the development of the OWC wave power plant on Islay Island, Wavegen built the LIMPET power plant near the original plant in November 2000 [32], as shown in Figure 3. Unlike the Islay prototype, the unit was located at the Atlantic monsoon outlet, rated at 500 kW, and has been operating successfully ever since. At the same time, the Portuguese Electricidade dos Acores company built the 400 kW OWC Wave power plant on Pico Island, which belongs to the Portuguese Wave Energy Research Center and is mainly used for the research and development of OWC power generation devices.

(3) Floating OWC device. After continuous accumulation and development, people began to explore the installation of OWC wave power generation devices in deep sea area.

Under the promotion of the International Energy Agency, from 1976 to 1979, led by Japan, the United Kingdom, Canada, Ireland and the United States jointly participated in the R & D team began to test the floating OWC power generation device, which is the world famous "Haiming" OWC wave power generation ship, its length of 80 m, weight 800 t, Eight OWC chambers rated at 125 kW were installed on the floating structure [34].