scholarly journals Development of a Computational Model for Investigation of and Oscillating Water Column Device with a Savonius Turbine

2022 ◽  
Vol 10 (1) ◽  
pp. 79
Author(s):  
Amanda Lopes dos Santos ◽  
Cristiano Fragassa ◽  
Andrei Luís Garcia Santos ◽  
Rodrigo Spotorno Vieira ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Computational Model ◽  
Water Column ◽  
Turbulent Flows ◽  
Constant Velocity ◽  
Speed Ratio ◽  
Oscillating Water Column ◽  
Similar Time ◽  
Averaged Equations ◽  
Large Channel ◽  
Volume Method

The present work aims to develop a computational model investigating turbulent flows in a problem that simulates an oscillating water column device (OWC) considering a Savonius turbine in the air duct region. Incompressible, two-dimensional, unsteady, and turbulent flows were considered for three different configurations: (1) free turbine inserted in a long and large channel for verification/validation of the model, (2) an enclosure domain that mimics an OWC device with a constant velocity at its inlet, and (3) the same domain as that in Case 2 with sinusoidal velocity imposed at the inlet. A dynamic rotational mesh in the turbine region was imposed. Time-averaged equations of the conservation of mass and balance of momentum with the k–ω Shear Stress Transport (SST) model for turbulence closure were solved with the finite volume method. The developed model led to promising results, predicting similar time–spatial-averaged power coefficients (CP¯) as those obtained in the literature for different magnitudes of the tip speed ratio (0.75 ≤ λ ≤ 2.00). The simulation of the enclosure domain increased CP¯ for all studied values of λ in comparison with a free turbine (Case 1). The imposition of sinusoidal velocity (Case 3) led to a similar performance as that obtained for constant velocity (Case 2).

scholarly journals DEVELOPMENT OF A NUMERICAL MODEL FOR THE STUDY OF AN OSCILLATING WATER COLUMN DEVICE CONSIDERING AN IMPULSE TURBINE

2019 ◽  
Vol 18 (1) ◽  
pp. 99
Author(s):  
A. L. dos Santos ◽  
L. A. Isoldi ◽  
L. A. O. Rocha ◽  
M. N. Gomes ◽  
R. S. Viera ◽  
...  
Keyword(s):  
Numerical Model ◽  
Energy Conversion ◽  
Water Column ◽  
Numerical Study ◽  
Velocity Ratio ◽  
Power Coefficient ◽  
Working Fluid ◽  
Speed Ratio ◽  
Oscillating Water Column ◽  
Impulse Turbine

The present work brings a numerical study of an energy conversion device which takes energy from the waves through an oscillating water column (OWC), considering an impulse turbine with rotation in the chimney region through the implementation of a movable mesh model. More precisely, a turbulent, transient and incompressible air flow is numerically simulated in a two-dimensional domain, which mimics an OWC device chamber. The objectives are the verification of the numerical model with movable mesh of the impulse turbine in the free domain from the comparison with the literature and, later, the study of the impulse turbine inserted in the geometry of the OWC device. In order to perform the numerical simulation on the generated domains, the Finite Volume Method (FVM) is used to solve the mass and momentum conservation equations. For the closure of the turbulence, the URANS (Unsteady Reynolds Averaged Navier-Stokes) model k-ω SST is used. To verify the numerical model employed, drag coefficients, lift, torque and power are obtained and compared with studies in the literature. The simulations are performed considering a flow with a Reynolds number of ReD = 867,000, air as the working fluid and a tip speed ratio of λ = 2. For the verification case, coefficients similar to those previously predicted in the literature were obtained. For the case where the OWC device was inserted it was possible to observe an intensification of the field of velocities in the turbine region, which led to an augmentation in the magnitude of all coefficients investigated (drag, lift, torque and power). For the case studied with the tip velocity ratio λ = 2, results indicated that power coefficient was augmented, indicating that the insertion of the turbine in a closed enclosure can benefit the energy conversion in an OWC device.

Analysis of Geometric Variation of Three Degrees of Freedom through the Constructal Design Method for a Oscillating Water Column Device with Double Hidropneumatic Chamber

2019 ◽  
Vol 396 ◽  
pp. 22-31
Author(s):  
Yuri T.B. Lima ◽  
Mateus das Neves Gomes ◽  
Camila F. Cardozo ◽  
Liércio André Isoldi ◽  
Elizaldo D. Santos ◽  
...  
Keyword(s):  
Water Column ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Geometric Optimization ◽  
Oscillating Water Column ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Volume Method ◽  
Geometric Variation

This paper presents a biphasic two-dimensional numerical study of sea wave energy converters with operating principle being Oscillating Water Column (CAO) devices with two couples chambers. For the study of the geometric optimization, the Constructal Design method is applied in association with the exhaustive search method to determine the geometric arrangement that leads to the greatest hydropneumatic power available. The objective function is the maximization of hydropneumatic power converted by the device. The constraints of the problem are the inflow volumes of the hydropneumatic chamber (VE1, VE2), the total volumes (VT1, VT2) and the thicknesses of the device columns (e1, e3). The degrees of freedom analyzed were H1/L1(ratio between height and length of the hydropneumatic chamber of the first device), H2/L2 (ratio between height and length of the hydropneumatic chamber of the second device), H2 (height of the column dividing the two devices) and e2 (thickness of the column dividing the devices). In the present work the degree of freedom H6 (depth of immersion of the device) is kept constant and equal to H6 = 9.86 m. The Finite Volume Method (FVM) was used in the numerical solution of the equations employed. For the treatment of the interaction between the air and water phases, the Volume of Fluid (VOF) method was applied. The results show that the maximum hydropneumatic power available was 5715.2 W obtained for degrees of freedom H1/L1 = H2/L2 = 0.2613 and e2 = 2.22 m. The case of lower performance has a power value equal to 4818.5 W with degrees of freedom equal to H1/L1 = H2/L2 = 0.2613 and e2 = 0.1 m.

VERIFICATION OF A PROPOSED COMPUTATIONAL MODEL FOR AN OSCILLATING WATER COLUMN TYPE ENERGY CONVERTER CONSIDERING SEA STATE DATA

2017 ◽  
Author(s):  
Sersana Sabedra de Oliveira ◽  
Edis Antunes Pinto Junior ◽  
Luciano Rodrigues ◽  
Phelype Haron Oleinik ◽  
Mateus das Neves Gomes ◽  
...  
Keyword(s):  
Computational Model ◽  
Water Column ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Sea State ◽  
State Data ◽  
Column Type

Comparison of the performance of oscillating water column devices based on arrangements of water columns

2020 ◽  
Vol 14 (3) ◽  
pp. 7082-7093
Author(s):  
Jahirwan Ut Jasron ◽  
Sudjito Soeparmani ◽  
Lilis Yuliati ◽  
Djarot B. Darmadi
Keyword(s):  
Wave Propagation ◽  
Water Column ◽  
Water Depth ◽  
Graphical Form ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Water Columns ◽  
Single Column ◽  
Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

Experimental study on the motions of a dual chamber floating oscillating water column device

2021 ◽  
Vol 170 ◽  
pp. 1257-1274 ◽  
Author(s):  
J.F.M. Gadelho ◽  
K. Rezanejad ◽  
S. Xu ◽  
M. Hinostroza ◽  
C. Guedes Soares
Keyword(s):  
Experimental Study ◽  
Water Column ◽  
Oscillating Water Column ◽  
Dual Chamber

Interaction of oblique waves with an Oscillating Water Column device

2021 ◽  
Vol 228 ◽  
pp. 108931
Author(s):  
Ayrton Alfonso Medina Rodríguez ◽  
Alejandro Martínez Flores ◽  
Jesús María Blanco Ilzarbe ◽  
Rodolfo Silva Casarín
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Oblique Waves

scholarly journals Performance assessment and optimization of a helical Savonius wind turbine by modifying the Bach’s section

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
M. Niyat Zadeh ◽  
M. Pourfallah ◽  
S. Safari Sabet ◽  
M. Gholinia ◽  
S. Mouloodi ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Performance Assessment ◽  
Turbulent Flows ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Basic Model ◽  
Turbine Performance ◽  
Primary Model ◽  
Savonius Wind Turbine

AbstractIn this paper, we attempted to measure the effect of Bach’s section, which presents a high-power coefficient in the standard Savonius model, on the performance of the helical Savonius wind turbine, by observing the parameters affecting turbine performance. Assessment methods based on the tip speed ratio, torque variation, flow field characterizations, and the power coefficient are performed. The present issue was stimulated using the turbulence model SST (k- ω) at 6, 8, and 10 m/s wind flow velocities via COMSOL software. Numerical simulation was validated employing previous articles. Outputs demonstrate that Bach-primary and Bach-developed wind turbine models have less flow separation at the spoke-end than the simple helical Savonius model, ultimately improving wind turbines’ total performance and reducing spoke-dynamic loads. Compared with the basic model, the Bach-developed model shows an 18.3% performance improvement in the maximum power coefficient. Bach’s primary model also offers a 12.4% increase in power production than the initial model’s best performance. Furthermore, the results indicate that changing the geometric parameters of the Bach model at high velocities (in turbulent flows) does not significantly affect improving performance.

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