scholarly journals Hydrodynamic Performance of Rectangular Heaving Buoys for an Integrated Floating Breakwater

2019 ◽  
Vol 7 (8) ◽  
pp. 239 ◽  
Author(s):  
Xiaoxia Zhang ◽  
Qiang Zeng ◽  
Zhen Liu
Keyword(s):  
Wave Energy ◽  
Numerical Results ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Wave Energy Converters ◽  
Floating Breakwater ◽  
Reaction Forces ◽  
Wave Conditions

Recently, the integrated development of wave energy converters and breakwaters has become popular, moving from traditional passive wave absorption to active energy capture. In this study, rectangular heaving buoys are considered as floating breakwater modules to absorb wave energy. A numerical wave tank is established based on Reynolds Averaged Navier-Stokes equation and User-Define-Function in ANSYS-Fluent commercial software. The numerical results show that incident wave conditions and submerged depth have significant effects on the heaving performance and wave energy absorption of a rectangular buoy. Flow structures around the buoy are shown to exhibit flow separations and vortex shedding, which can provide more information on buoy optimization. Power take-off (PTO) reaction forces are assumed to be a linear function of the translation velocities of the buoy. Numerical results demonstrate that a suitable PTO module can improve the wave power absorption by up to 34.2% for certain buoy and wave conditions, which is valuable for further investigations.

scholarly journals Optimizing the Power Take Off of a Wave Energy Converter With Regard to the Wave Climate

2005 ◽  
Vol 128 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Gaelle Duclos ◽  
Aurelien Babarit ◽  
Alain H. Clément
Keyword(s):  
Wave Energy ◽  
Simple Wave ◽  
Wave Climate ◽  
Wave Energy Converter ◽  
Optimal Parameters ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Classical Wave ◽  
Project Site ◽  
Wave Conditions

Considered as a source of renewable energy, wave is a resource featuring high variability at all time scales. Furthermore wave climate also changes significantly from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period at the project site. In this paper we show that optimizing the device necessitates accounting for all possible wave conditions weighted by their annual occurrence frequency, as generally given by the classical wave climate scatter diagrams. A generic and very simple wave energy converter is considered here. It is shown how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the productive motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three sites with very different wave climate.

Numerical Study on Control of Sunroof Buffeting

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
K. Vijaykumar ◽  
S. Poonkodi ◽  
A.T. Sriram
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dominant Frequency ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Flow Modification ◽  
Numerical Result ◽  
Modification Technique ◽  
Commercial Solver

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

Conjugate Free Convection Heat Transfer and Thermodynamic Analysis of Infrared Suppression Device with Cylindrical Funnels

2022 ◽  
Author(s):  
Vikrant Chandrakar ◽  
Arnab Mukherjee ◽  
Jnana Ranjan Senapati ◽  
Ashok Kumar Barik
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Bejan Number ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Geometric Ratio ◽  
Flow Rate Increase ◽  
Free Convection Heat

Abstract A convection system can be designed as an energy-efficient one by making a considerable reduction in exergy losses. In this context, entropy generation analysis is performed on the infrared suppression system numerically. In addition, results due to heat transfer are also shown. The numerical solution of the Navier-stokes equation, energy equation, and turbulence equation is executed using ANSYS Fluent 15.0. To perform the numerical analysis, different parameters such as the number of funnels, Rayleigh number (Ra), inner surface temperature, and geometric ratio are varied in the practical range. Results are shown in terms of heat transfer, entropy generation, irreversibility (due to heat transfer and fluid friction), and Bejan number with some relevant parameters. Streamlines and temperature contours are also provided for better visualization of temperature and flow field around the device. Results show that heat transfer and mass flow rate increase with the increase in Ra. Entropy generation and the irreversibility rise with an increase in the number of funnels and geometric ratio. Also, the Bejan number decreases with an increase in Ra and the number of funnels. A cooling time is also obtained using the lumped capacitance method.

Numerical Research of the Effect of the Outlet Diameter of Diffuser on the Performance and the Radial Force in a Single-Stage Centrifugal Pump

2014 ◽  
Author(s):  
Jiang Wei ◽  
Li Guojun ◽  
Liu Pengfei ◽  
Zhang Lisheng ◽  
Qing Hongyang
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Numerical Results ◽  
Operating Conditions ◽  
Single Stage ◽  
Navier Stokes ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Vaned Diffuser ◽  
Unsteady Numerical Simulation

In this paper, a single-stage pump with diffuser vanes of different outlet diameters has been investigated both numerically and experimentally. The influence of the diffuser vane outlet diameter on pump hydraulic performance and on the radial force of the impeller is explored. Pumps equipped with three different diffusers but with impellers and volutes of the same parameters were simulated by 3D Navier-Stokes solver ANSYS-FLUENT in order to study the effect of the outlet diameter of vaned diffuser on performance of the centrifugal pump. Structured grids of high quality were applied on the whole computational domain. Experimental results were acquired by prototype experiments and were then compared with the numerical results. Both experimental and numerical results show that the performance of a pump with a diffuser of smaller outlet diameter is better than of bigger outlet diameter under all operating conditions. The radial force imposed on the impeller obtained by unsteady numerical simulation was analyzed. The results also indicated that an appropriate decrease in the outlet diameter of the diffuser vane could increase the radial force.

scholarly journals WAVE PRESSURE DISTRIBUTIONS ON A U-OWC BREAKWATER: EXPERIMENTAL DATA VS CFD MODEL

2018 ◽  
pp. 15
Author(s):  
Pasquale G. Fabio Filianoti ◽  
Luana Gurnari
Keyword(s):  
Pressure Distribution ◽  
High Performance ◽  
Ideal Gas ◽  
Navier Stokes ◽  
Eastern Coast ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Wave Energy Converters ◽  
Vof Model ◽  
Line Force

U-OWCs are Wave Energy Converters belong in to the family of Oscillating Water Column. The interaction between waves and a U-OWC breakwater produces an unknown pressure distribution on the breakwater wall, due to the motion inside the plant. In order to evaluate the force acting on a U-OWC breakwater produced by regular waves, we carried out an experiment in a 2D numerical flume. The computational domain is equipped by a piston-type wavemaker, in the left extremity side and a U-OWC breakwater on the opposite side. The water-air interaction is taken into account by means of the Volume Of Fluid (VOF) model implemented in the commercial CFD code Ansys Fluent. Both air and water flow fields are assumed to be unsteady and are computed by solving the Reynolds-Averaged Navier-Stokes (RANS) equations. In the numerical model, air is considered as an ideal gas, in order to take into account the compressibility inside the plenum chamber. Results were compared with a theoretical model on a traditional vertical breakwater and experimental results obtained through an experiment directly at sea, off the beach of Reggio Calabria, in the eastern coast of the Straits of Messina (Southern Italy). As observed in the physical experiment at sea, the pressure distribution are strongly influenced by the absorption of the plant. Indeed, in case of high performance of the U-OWC, we found a deformation of the pressure distribution in respect to the theoretical one, especially near the outer opening of the plant. This deformation produces a lower in line force on the structure.

scholarly journals Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

2018 ◽  
Vol 172 ◽  
pp. 06002
Author(s):  
P.Madhan Kumar ◽  
Abdus Samad
Keyword(s):  
Wave Energy ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Wells Turbine ◽  
Reference Case ◽  
Navier Stokes Equation ◽  
World Energy ◽  
Entrapped Air ◽  
Experimental Values

To fulfill the ever growing demands of world energy consumption, the wave energy should be extracted economically. The oscillating water column is most commonly used to xtract energy from waves. It consists of a chamber in which waves drives the entrapped air column to rotate the Wells turbine. The Wells turbine is a self-rectifying low-pressure axial reaction turbine with 90ο stagger angle. These turbines consist of symmetrical airfoil profile to achieve unidirectional rotation for the bi-directional airflow. The turbine performance predominantly depends on the aerodynamic characteristics of the airfoil profile used. In this study, the performance of Wells turbine with various symmetrical airfoil profiles was analysed using ANSYS CFX 14.5. The CFD analysis was performed by solving three dimensional steady Reynolds averaged Navier-Stokes equation with k-ω SST turbulence closure model. The reference geometry has NACA0015 as blade profile and the CFD results were compared with the experimental values. The performance characteristics of the new airfoil profiles were compared with the reference case to analyse the suitability of airfoils in wave energy extraction. The NACA0021 airfoil profile showed better performance in the post-stall regime compared to the NACA0015 and the S1046 airfoil profiles.

Numerical Simulation Calculation of Hydroplane Direct Route Motion Based on FLUENT

2012 ◽  
Vol 569 ◽  
pp. 368-375
Author(s):  
Yu Qin ◽  
Xiao Liang ◽  
Jia Ning Zhang
Keyword(s):  
Numerical Simulation ◽  
Performance Prediction ◽  
Dynamic Pressure ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Velocity Change ◽  
Direct Route ◽  
Field Situation ◽  
Simulation Calculation

Aiming at hydrodynamic performance prediction for hydroplane motion, numerical simulation calculation for direct route motion of a hydroplane was carried out under FLUENT software platform by using VOF method and RNG k-ε model and solving Navier-Stokes equation. Evolution of ship resistance was obtained as the velocity change, and flow field situation and dynamic pressure variation of hydroplane hull bottom were reflected intuitively. By comparing the results of FLUENT calculation and ship model experiment and theoretical estimation, analyzing, especially wake current, it was verified that numerical simulation calculation of hydroplane direct route motion and hydrodynamic performance prediction based on FLUENT are feasible and precise enough.

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