Research and Simulation Analysis on a Novel U-Tube Type Dual-Chamber Oscillating Water Column Wave Energy Conversion Device

Abstract

With the development of wave energy, a promising renewable resource, oscillating water column (OWC) devices, has been extensively studied for its potential in harnessing this energy. However, traditional OWC devices face challenges such as corrosion and damage from prolonged exposure to harsh marine environments, limiting their long-term viability and efficiency. To address these limitations, this paper proposes a novel U-tube type dual chamber OWC wave energy conversion device integrated within a marine vehicle. The research involves the design of a U-tube dual-chamber OWC device, which utilizes the pitch motion of a marine vehicle to drive the oscillation of water columns within the U-tube, generating reciprocating airflow that drives an air turbine. Numerical simulations using computational fluid dynamics (CFD) were conducted to analyze the effects of various structural dimensions, including device length, width, air chamber height, U-tube channel width, and bottom channel height, on the aerodynamic power output. The simulations considered real sea conditions, focusing on low-frequency waves prevalent in China’s sea areas. Simulation results reveal that increasing the device’s length and width substantially boosts aerodynamic power, while air chamber height and U-tube channel width have minor effects. These findings provide valuable insights into the optimal design of U-tube dual-chamber OWC devices for efficient wave energy conversion, laying the foundation for future physical prototype development and experimental validation.

1. Introduction

The field of marine renewable energy encompasses various forms of energy derived from the ocean, including tidal, marine current, wave, ocean thermal and salinity gradient resources [1,2,3]. Among these energy sources, wave energy stands out for its high energy density and relatively low environmental impact [4,5]. As one of the most promising marine energy sources, wave energy has garnered significant attention due to its wide spatial distribution and abundant reserves. It is estimated that the global wave energy reserves amount to approximately 2 terawatts (TW), with a technical potential of up to 90% availability throughout the year [6,7]. Due to climate change, renewable energy sources such as solar, wave, and tidal power are being actively explored worldwide for electricity generation [8]. Therefore, research on wave energy holds significant importance.

Over the past years, various innovative wave energy converters (WECs) have been developed and tested [9,10]. Based on deployment location, WECs may be classified into floating and shore-fixed configurations [11,12,13]. Among all existing WEC technologies, oscillating water column (OWC) devices have received extensive research attention [10]. OWC technology is widely recognized as a promising wave energy conversion system with substantial resource potential [9]. As shown in Figure 1, OWC devices have already been applied in practical applications, including, for instance, the Limpet Wave Energy Converter [14], the REWEC3 [15], OE Buoy [16]. However, existing OWC designs require direct contact with seawater, making them highly susceptible to damage under extreme sea conditions and corrosion during prolonged exposure. To address this limitation, this paper proposes an OWC device integrating into the interior of marine vessel, aiming to significantly reduce the impact of extreme sea conditions and prevent corrosion caused by direct exposure to seawater.

The development of the sloshing tank experimental apparatus traces its origins to the pioneering investigations of William Froude. The central challenge of Froude’s research was to mitigate the inherent rolling motion encountered by ships navigating through rough seas [17]. In recent decades, research on the performance characteristics of sloshing tank systems has stimulated extensive investigation within the marine engineering community. Early numerical modeling studies of fluid motion in U-tube tanks were initiated by Stigte [18]. Subsequently, Lloyd [19] developed a simplified one-dimensional model based on the Euler momentum equation to study rolling oscillations in U-tube tanks. With significant advancements in computational capabilities, Zhong [20] conducted more in-depth research using the finite element method for two-dimensional computational fluid dynamics (CFD) simulations. Their approach implemented a finite element discretization of the Navier–Stokes equations via the Galerkin weighted residual formulation. This method was also applied by Van Daalen et al. [21] and Bhushnan et al. [22] when studying the performance of U-shaped water tanks through fully three-dimensional (3D) CFD simulations and validated by experimental results.

Traditionally, U-shaped tank research focused on ship roll stabilization [23]. In contrast, this study proposes an integrated solution embedding a WEC device within a ship’s hull to provide backup power for navigational instruments. By coupling vessel roll motion to an OWC wave energy converter integrated with a U-tank system, this approach expands U-tank applications beyond conventional stabilization.

Inspired by U-shaped roll stabilization tanks [24,25], this paper proposes a U-tube dual-chamber oscillating water column device (U-OWC). The U-OWC structure eliminates the need for direct contact with seawater, avoiding direct wave action. Similar to conventional OWC devices, the air turbine of the U-OWC is installed in the passage connecting the air chamber to the atmosphere. Crucially, unlike typical OWC deployments, the novelty of this converter lies in its placement inside a ship, isolated from seawater. The vessel’s motion during navigation causes the internal water column to oscillate, continuously compressing and expanding the air within the two air chambers. The resulting pressure difference drives reciprocating airflow through the turbine. When the airflow passes through the air turbine, it drives the turbine’s rotation, thereby powering a generator to produce electricity.

The remainder of this paper is organized as follows: Section 2 introduces the proposed U-OWC; Section 3 presents the numerical model; Section 4 describes the simulation setup for the newly proposed U-tube dual-chamber oscillating water column device; Section 5 details the numerical simulation calculations for the same; and Section 6 presents the results and discussions.

2. The Design of U-Tube Dual Chamber OWC

Most conventional OWC devices operate through direct interaction with seawater, where waves directly impinge upon the device, inducing vertical oscillations in the internal water column as a result of external wave forces [26]. This motion periodically compresses and releases the air within the air chamber, generating bidirectional airflow. The airflow is then converted into unidirectional rotation by a turbine (typically a Wells turbine or an impulse turbine) [27,28].

In contrast, the proposed U-tube dual-chamber OWC is installed inside a marine vessel. When waves act upon the vessel, they induce oscillatory motions (e.g., roll, pitch, or heave), which are transmitted to the U-OWC. This design converts wave energy into mechanical energy and ultimately electricity through its unique structure (as shown in Figure 2).

The U-OWC (Figure 2) consists of a hollow U-tube with two identical rectangular air chambers at its ends. Each chamber has a cylindrical outlet of a uniform cross-sectional area. Two air turbines are installed separately in the duct connecting each air chamber to the atmosphere, housed in the cylindrical channels above each chamber in the simulated configuration.

3. Numerical Model

For this research, the thermodynamic behavior of the gaseous medium within the computational framework is governed by the ideal gas equation of state. Given that airflow velocities in the chamber remain below Mach 0.3 (approximately 102 m/s), a threshold permitting treatment as an incompressible fluid, air compressibility effects are consequently neglected throughout the simulations [29]. The aerodynamic power of the air chambers is calculated as follows [30]:

$${\mathrm{P}}_{\mathrm{i}}={\displaystyle \frac{1}{\mathrm{N}\mathrm{T}}}{\int }_{{\mathrm{T}}_0}^{{\mathrm{T}}_0+\mathrm{N}\mathrm{T}}\Delta \mathrm{P}(\mathrm{t})\mathrm{Q}(\mathrm{t})\mathrm{d}\mathrm{t}$$

(1)

$$\mathrm{Q}\left(\mathrm{t}\right)=\mathrm{U}\left(\mathrm{t}\right)\mathrm{S}$$

(2)

where ${\mathrm{P}}_{\mathrm{i}}$ is the aerodynamic power of one of the two air chambers, ΔP is defined as the differential pressure between the internal chamber pressure and atmospheric pressure, $\mathrm{Q}\left(\mathrm{t}\right)$ is the real-time air flow rate through the chamber’s top opening, $\mathrm{U}\left(\mathrm{t}\right)$ is the real-time vertical air velocity through the orifice, and S is the cross-sectional area of the orifice.

The generation of air flow caused by pressure changes in the air chamber originates from the rising and falling movement of the free liquid surface within the air chamber. The gas flow rate can be derived based on the movement of the liquid level or changes in the air chamber volume [31]:

$${\mathrm{K}}_{\mathrm{t}}p=\mathrm{Q}=-{\displaystyle \frac{\mathrm{d}\mathrm{V}}{\mathrm{d}\mathrm{t}}}$$

(3)

where ${\mathrm{K}}_{\mathrm{t}}$ is the air turbine coefficient and $p$ is the pressure drop in the air chamber, Q indicates the air volume flow rate, and V indicates the air chamber volume that changes with the rise and fall of the liquid level.

In the U-OWC, the two pneumatic chambers operate independently. Consequently, the total efficiency of the dual-chamber OWC system equals the arithmetic sum of the individual efficiencies of each chamber:

$$\mathrm{P}={\mathrm{P}}_1+{\mathrm{P}}_2$$

(4)

The continuity and momentum equations in incompressible flows are defined as in Equation (4) and Equation (5), respectively [32]:

$${\displaystyle \frac{\partial {\mathrm{u}}_{\mathrm{i}}}{\partial {\mathrm{x}}_{\mathrm{i}}}}=0$$

(5)

$$\mathsf{\rho }{\displaystyle \frac{\mathrm{D}{\mathrm{u}}_{\mathrm{i}}}{\mathrm{D}\mathrm{t}}}=-{\displaystyle \frac{\partial \mathrm{P}}{\partial {\mathrm{x}}_{\mathrm{i}}}}+\left(\mathsf{\mu }+{\mathsf{\mu }}_{\mathrm{t}}\right){\displaystyle \frac{\partial }{\partial {\mathrm{x}}_{\mathrm{j}}}}\left({\displaystyle \frac{\partial {\mathrm{u}}_{\mathrm{i}}}{\partial {\mathrm{x}}_{\mathrm{j}}}}+{\displaystyle \frac{\partial {\mathrm{u}}_{\mathrm{j}}}{\partial {\mathrm{x}}_{\mathrm{i}}}}\right)+{\mathrm{f}}_{\mathrm{i}}$$

(6)

where ${\mathrm{u}}_{\mathrm{i}}$, t, P, ${\mathrm{f}}_{\mathrm{i}}$, p, $\mathsf{\mu },$ and $\mathsf{\mu }$_t are velocity components, time, static pressure, body force density, dynamic viscosity, and turbulence viscosity, respectively. In this study, $\mathsf{\mu }$_t is calculated using the standard k-ε model.

The Volume of Fluid (VOF) model tracks two or more immiscible fluids by solving a unified set of momentum equations and monitoring the volume fraction of each fluid across the computational domain. Typical applications include predicting jet breakup, large bubble dynamics in liquids, post-dam-break liquid motion, and steady/transient liquid-gas interface tracking. In the VOF approach, each computational cell is assigned a volume fraction for each phase to delineate their spatial distribution. The interfacial flow dynamics exhibit convective interactions between the phases, quantified by the volume fraction α (as defined in Equation (6)) [32].

$${\displaystyle \frac{\partial \mathsf{\alpha }}{\partial \mathrm{t}}}+{\mathrm{u}}_{\mathrm{j}}{\displaystyle \frac{\partial \mathsf{\alpha }}{\partial {\mathrm{x}}_{\mathrm{j}}}}=0$$

(7)

If the fluid’s volume fraction in the cell is denoted, then the following three conditions are possible:

α = 0, The cell is empty (of the fluid);

α = 1, The cell is full (of the fluid);

0 < α < 1, The cell contains the interface between the fluid and one or more other fluids.

The local volume fraction α dictates the assignment of material properties and variables to each control volume within the computational domain.

With respect to dynamic meshes, the integral form of the conservation equation for a general scalar on an arbitrary control volume whose boundary is moving can be written as $\mathsf{\varphi }$V:

$${\displaystyle \frac{\mathrm{d}}{\mathrm{d}\mathrm{t}}}{\int }_{\mathrm{V}}\mathsf{\rho }\mathsf{\varphi }\mathrm{d}\mathrm{V}+{\int }_{\partial \mathrm{V}}\mathsf{\rho }\mathsf{\varphi }\left(\overrightarrow{\mathrm{u}}-{\overrightarrow{\mathrm{u}}}_{\mathrm{g}}\right)\cdot \mathrm{d}\overrightarrow{\mathrm{A}}={\int }_{\partial \mathrm{V}}\mathsf{\Gamma }\nabla \mathsf{\varphi }\cdot \mathrm{d}\overrightarrow{\mathrm{A}}+{\int }_{\mathrm{V}}{\mathrm{S}}_{\mathsf{\varphi }}\mathrm{d}\mathrm{V}$$

(8)

where $\mathsf{\rho }$ is the fluid density, $\overrightarrow{\mathrm{u}}$ is the flow velocity vector, ${\overrightarrow{\mathrm{u}}}_{\mathrm{g}}$ is the mesh velocity of the moving mesh, $\mathsf{\Gamma }$ is the diffusion coefficient, ${\mathrm{S}}_{\mathsf{\varphi }}$ is the source term of p.

4. Simulation Settings

To assess the impact of structural dimensions on aerodynamic power output at the device’s air chamber outlet, numerical simulations were conducted for models with the following parameters (as shown in Figure 3): Total device length (L): 1100 mm, 1200 mm, 1300 mm, 1400 mm; Total device width (W): 800 mm, 1000 mm, 1200 mm, 1400 mm; Air chamber height (H): 200 mm, 300 mm, 400 mm, 500 mm; U-tube channel width (T): 300 mm, 400 mm, 500 mm, 600 mm; Bottom channel height (D): 100 mm, 200 mm, 300 mm, 400 mm. During simulations, the air turbine was replaced with an orifice plate, and its influence on system behavior was disregarded. Optimal wave energy conversion efficiency in OWC systems is achieved at orifice ratios (orifice area/water column area) of 0.5–2.0%, where the damping characteristics are most favorable. Consequently, the orifice configuration in this work was set at 1% of the air chamber cross-section [33]. The still water depth within the device was consistently maintained at 150 mm above the bottom channel height to minimize interference with other variables.

The final device performance was determined through systematic parameter variations. To investigate the impact of individual parameters on equipment performance, a single-variable optimization strategy was employed. Each parameter’s range was configured based on actual equipment constraints. Our approach accelerates convergence to near-optimal solutions while significantly reducing computational time. Due to computational and time limitations, this study did not account for potential coupling effects between multiple parameters. Each marine region across the globe has distinct wave patterns and energy levels [34]. In real marine environments, ocean waves predominantly exhibit low-frequency characteristics. Across China’s coastal waters, the dominant wave periods range from 3 s to 6 s [35], with significant wave heights typically spanning 0.5 m to 4 m. Under such sea states, over 80% of the total wave energy is concentrated within this spectral band [36].

The external excitation forces acting on the described device primarily originate from vessel roll motion. As the device is rigidly affixed within the ship’s hull with no relative displacement, the ship’s oscillatory motion directly induces equivalent forced oscillations in the device. The roll period and roll amplitude serve as kinematic input conditions for the device rather than resulting from direct wave impacts. Consequently, no investigations were conducted regarding wave height or wave period parameters. Under head sea conditions (χ = 0° or 180°), vessels exhibit minimal roll motion. Conversely, beam sea encounters (χ = 90°) induce substantial roll amplitudes exceeding 10°. To facilitate unambiguous parametric sensitivity analysis of the wave energy converter (WEC), simulations in this study adopted a standardized 10° roll amplitude [37]. These parameters align with motion characteristics documented in the China Classification Society *R001-2024 Rules for Classification of Sea-going Steel Ships*, where typical roll response ranges for small vessels are quantified as follows: Roll amplitude range: 0° to 30°; Roll period: 3 to 6 s; Corresponding roll frequency: 0.167 Hz to 0.333 Hz.

This research specifically addresses how internal configuration parameters of U-OWC systems influence their operational efficiency. Analyses pertaining to wave-induced structural loads and hydrodynamic responses of vessels are explicitly excluded from the present investigation. In this study, the oscillation angle was fixed at 10°, and the oscillation period was varied between 3 s and 6 s to simulate realistic sea conditions. The fluid domain within the device was extracted in ANSYS Fluent 2023R1, with simulation boundaries defined as no-slip walls and the two outlets set as pressure inlet conditions. Initializing the pressure differential at the orifice to 0 Pa establishes a pressure baseline referenced to atmospheric pressure, which dynamically fluctuates in synchronization with pneumatic chamber pressure variations during simulations. This configuration enables bidirectional gas exchange dynamics throughout the liquid oscillation cycle, where gas ingestion and expulsion processes periodically alternate in a phase-locked manner. During meshing, the grid near the orifices was refined to improve data accuracy, using structured quadrilateral elements to ensure convergence in subsequent transient dynamic mesh simulations (as shown in Figure 4).

5. Simulation Analysis

5.1. Mesh Effect of the Numerical Model

To mitigate computational costs while preserving accuracy, a grid independence study was conducted to assess mesh parameter sensitivity. Insufficient mesh density compromises solution accuracy, whereas excessive elements incur prohibitive computational overhead [38]. Three models with 0.3 M, 0.6 M, and 0.9 M cells were simulated. As illustrated in Figure 5, the air mass flow rate curves exhibit consistent trends across all resolutions, with the 0.6 M and 0.9 M models demonstrating negligible divergence (<2%). Given the 0.6 M mesh’s superior computational efficiency and minimal accuracy loss relative to the 0.9 M case, it was selected as the optimal configuration. In addition, the symmetry of inflow and outflow volume rates within each oscillation cycle confirms that the constructed model strictly adheres to the principles of mass conservation.

5.2. The Effect of the Overall Device Length on the Aerodynamic Power

The impact of variations in the overall device length on the overall aerodynamic power was investigated.

Table 1. Length parameters and research results.

	L(1100)	L(1200)	L(1300)	L(1400)
Device length (mm)	1100	1200	1300	1400
Cross-sectional area of the air chamber exit passage (m2)	0.00699	0.00699	0.00699	0.00699
Maximum aerodynamic power (W)	5.7	10.4	17.4	26.8

shows the cross-sectional area of the air chamber outlet channel and the corresponding maximum aerodynamic power for four different device lengths. When the length was set to 1400 mm, the device achieved optimal performance, with a peak aerodynamic power of 26.8 W. Longer device lengths correlated with increased maximum power output.

Figure 6 illustrates the overall aerodynamic power curves of the device, generated via simulation software, for varying device lengths. Notably, the curve for the 1100 mm device exhibits minimal fluctuations. As device length increases, the aerodynamic power curve demonstrates a more pronounced upward trend. Significant disparities in power output were observed among the four lengths within the 3 s to 4.5 s oscillation period range. Beyond 4.5 s, the power outputs converged. Comparative analysis confirmed that the 1400 mm (L1400) configuration delivered the best performance.

Increasing the conduit length prolongs hydraulic transit time, amplifying phase-opposition oscillations in the vertical water columns and enhancing pneumatic throughput. Numerical analysis of the impact of device length variations reveals that length adjustments significantly influence the overall aerodynamic power output. Notably, a device length of 1400 mm yields the highest aerodynamic power, offering critical insights for optimizing device width in future studies.

5.3. The Impact of the Overall Width of the Device on Aerodynamic Power

The analysis was conducted to assess the impact of varying device width on the overall aerodynamic power output.

Table 2. Width parameters and research results.

	W(800)	W(1000)	W(1200)	W(1400)
Device width (mm)	800	1000	1200	1400
Cross-sectional area of the air chamber exit passage (m2)	0.00478	0.00599	0.00717	0.00839
Maximum aerodynamic power (W)	14.2	19.9	24	27.6

summarizes the cross-sectional area of the air chamber outlet channel and the corresponding maximum aerodynamic power for four device widths. A width of 1400 mm yields the optimal performance, achieving a peak aerodynamic power of 27.6 W. However, compared to length adjustments, varying the width resulted in smaller power improvements.

Figure 7 presents the simulated power curves for different widths. Aerodynamic power increased with wider configurations, with the 1400 mm (W1400) design outperforming others.

Wider conduits strengthen inertial coupling between water columns, promoting phase-opposition synchronization and maximizing pneumatic flux. Numerical analysis further validates that device width variations substantially influence aerodynamic power. Specifically, the 1400 mm width maximizes power output, providing critical insights for optimizing the air chamber height in future studies.

5.4. The Impact of the Overall Height of the Device on Aerodynamic Power

Table 3. Height parameters and research results.

	H(200)	H(300)	H(400)	H(500)
Device height (mm)	200	300	400	500
Cross-sectional area of the air chamber exit passage (m2)	0.00839	0.00839	0.00839	0.00839
Maximum aerodynamic power (W)	27.4	27.6	26	27.4

summarizes four air chamber heights, their corresponding outlet cross-sectional areas, and the associated maximum aerodynamic power. Notably, an air chamber height of 500 mm yields the highest performance, achieving a peak aerodynamic power of 27.4 W. Increasing the air chamber height beyond this point does not proportionally enhance aerodynamic power, indicating a plateau in efficiency.

Figure 8 depicts the simulated aerodynamic power curves for the four air chamber heights. The data show minimal variation in the power curves across height adjustments, suggesting that air chamber height has a negligible impact on the final aerodynamic power output. A comprehensive comparison confirms that the 500 mm (H500) configuration is optimal.

Variations in air chamber height exhibit negligible direct influence on the displacement amplitudes of the flanking water columns. However, when chamber height exceeds the optimal design value, the differential pressure gradient across the chamber boundary diminishes, impairing pneumatic energy transfer efficiency. Numerical analysis reinforces these findings: air chamber height variations exert little influence on overall aerodynamic power. The 500 mm height maximizes power generation, providing critical insights for optimizing internal channel heights in future designs.

5.5. The Impact of the Channel Width Inside the Device on the Aerodynamic Power

Table 4. Channel width parameters and research results.

	T(300)	T(400)	T(500)	T(600)
Device passage width (mm)	300	400	500	600
Cross-sectional area of the air chamber exit passage (m2)	0.00418	0.00559	0.00699	0.00839
Maximum aerodynamic power (W)	27.6	32	26.8	25.4

summarizes the cross-sectional area of the air chamber outlet channel and the corresponding maximum aerodynamic power for four U-tube channel widths. A width of 400 mm achieves the highest performance, delivering a peak aerodynamic power of 32 W.

Figure 9 shows the simulated aerodynamic power curves for the four U-tube channel widths. The data reveal minimal variations in the power curves across width adjustments, though differences are more pronounced at lower oscillation periods. At higher oscillation periods, the curves converge, indicating negligible impact of channel width on aerodynamic power. However, the 400 mm design consistently outperformed others, especially at lower periods.

While wider U-tube channel width increases the airflow rate within the air chambers, it concurrently reduces the differential pressure between the chambers and the external environment. This trade-off ultimately diminishes the net pneumatic power output, as established through hydrodynamic scaling laws. Numerical analysis validates these findings: setting the U-tube channel width to 400 mm maximizes aerodynamic power output, providing critical insights for optimizing the air chamber angle in future designs.

5.6. The Impact of the Channel Height Inside the Device on the Aerodynamic Power

Table 5. Channel height parameters and research results.

	D(100)	D(200)	D(300)	D(400)
Bottom channel height (mm)	100	200	300	400
Cross-sectional area of the air chamber exit passage (m2)	0.00559	0.00559	0.00559	0.00559
Maximum aerodynamic power (W)	40	34	30	28

summarizes four bottom channel heights, corresponding air chamber outlet cross-sectional areas and the associated maximum aerodynamic power. Notably, a bottom channel height of 100 mm yields the highest performance, achieving a peak aerodynamic power of 40 W.

Figure 10 displays the simulated aerodynamic power curves for the four bottom channel heights. The data reveal that reducing the bottom channel height significantly enhances aerodynamic power at lower oscillation periods, while the 100 mm configuration consistently outperforms the others across all conditions. A comprehensive comparison confirms that D100 is optimal.

The reduction in bottom channel height accelerates the water flow velocity within the conduit, resulting in more pronounced vertical displacements of the flanking water columns. This intensified oscillation enhances pneumatic power generation during the operational cycle. Numerical analysis validates these findings: setting the bottom channel height to 100 mm maximizes aerodynamic power output, particularly at lower oscillation periods.

5.7. The Impact of Sloshing Angle on the Aerodynamic Power of the Device

For vessels with wave incidence angles of 45° or 135° (χ = 45° or 135°), the roll angle of the vessel tends to be approximately 5 degrees.

Table 6. Oscillation angle parameters and research results.

	Deg(10)	Deg(5)
Sloshing angle (°)	10	5
Cross-sectional area of the air chamber exit passage (m2)	0.00559	0.00559
Maximum aerodynamic power (W)	40	13.4

presents two different oscillation angles, the corresponding cross-sectional area of the air chamber outlet channel of the device, and the corresponding maximum aerodynamic power. As shown in Table 6, when the oscillation angle of the device is 10°, the overall aerodynamic power generated by the device is higher than that generated when the oscillation angle is 5°.

Figure 11 presents a curve diagram of the overall aerodynamic power of the device calculated by simulation software under different oscillation angles. By observing the overall curve diagram, it can be seen that higher aerodynamic power can be generated when the oscillation angle is larger, while the curve tends to be flatter when the oscillation angle is smaller.

The larger the oscillation angle, the greater the swing amplitude of the water column relative to the equilibrium position inside the device, and the faster the speed at which the water column rises and falls, thus generating more aerodynamic power. Through numerical calculation and analysis of the influence of the oscillation angle, it is found that when the oscillation angle is larger, the device can generate higher aerodynamic power.

5.8. Simulation Conclusions

Based on the analysis of multiple sets of data through simulation and modeling, the following conclusions can be drawn:

(1)

The numerical simulation results show that changing the length, width of the device, and the height of the bottom channel of the device has a significant impact on the generated aerodynamic power. Specifically, increasing the length and width of the device can increase the generated aerodynamic power; reducing the height of the bottom channel of the device can also increase the generated aerodynamic power. Adjusting these three groups of variables also has a relatively obvious effect on the change of aerodynamic power.

(2)

Numerical simulations indicate that modifying the air chamber height and U-tube width has minimal effect on aerodynamic power. However, subtle refinements to the U-tube width may yield marginal improvements in power generation under specific conditions.

6. Conclusions

This paper introduces a U-tube dual-chamber oscillating water column wave energy conversion device designed to expand application scenarios for OWC-based wave energy harvesting. Through numerical simulations, the study analyzes the device’s aerodynamic power output to identify optimal structural parameters and their corresponding efficiency, providing a foundational design framework for practical wave energy systems. The main achievements of this paper include:

(1)

A novel U-tube dual-chamber OWC device is proposed, targeting enhanced adaptability and efficiency in wave energy conversion, thereby broadening the operational scope of existing OWC technologies.

(2)

Fluid dynamics modeling and simulations were conducted to evaluate the device’s structural and operational dynamics. By systematically varying parameters such as length, width, and bottom channel height, the study quantifies their impact on aerodynamic power efficiency, establishing data-driven design guidelines.

Future work will focus on manufacturing a physical prototype for semi-physical experimental verification on a six-degree-of-freedom platform. Due to computational constraints and time limitations, this study did not take into account the possible coupled and varying relationships among multiple parameters. The parameters of the practical prototype will be optimized by optimization algorithms such as particle swarm optimization (PSO) to achieve better power conversion efficiency.

The prototype will incorporate an air turbine system to measure actual power generation, enabling iterative refinement of the device’s structural and operational parameters. The influence of the ship’s roll angle under different wave incidence directions will also be verified in our future research.