A Comparison of Different Approaches to Estimate the Efficiency of Wells Turbines

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Fabio Licheri ◽  
Francesco Cambuli ◽  
Pierpaolo Puddu ◽  
Tiziano Ghisu
Keyword(s):  
Numerical Simulations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Electrical Energy ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Ocean Wave Energy ◽  
Efficiency Measures ◽  
Entropy Conservation ◽  
Theoretical Analyses

Abstract Wells turbines are among the most interesting power takeoff devices used in oscillating water column (OWC) systems for the conversion of ocean-wave energy into electrical energy. Several configurations have been studied during the last decades, both experimentally and numerically. Different methodologies have been proposed to estimate the efficiency of this turbine, as well as different approaches to evaluate the intermediate quantities required. Recent works have evaluated the so-called second-law efficiency of a Wells turbine, and compared it to the more often used first-law efficiency. In this study, theoretical analyses and numerical simulations have been used to demonstrate how these two efficiency measures should lead to equivalent values, given the low pressure ratio of the machine. In numerical simulations, small discrepancies can exist, but they are due to the difficulty of ensuring entropy conservation on complex three-dimensional meshes. The efficiencies of different rotor geometries are analyzed based on the proposed measures, and the main sources of loss are identified.

scholarly journals STUDI POTENSI PEMBANGKIT LISTRIK TENAGA GELOMBANG LAUT DENGAN METODA OSCILATING WATER COLUMN DI PERAIRAN KENDARI INDONESIA

2019 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Faulincia Faulincia
Keyword(s):  
Water Column ◽  
Alternative Energy ◽  
Water System ◽  
Electrical Energy ◽  
Ocean Wave ◽  
Oscillating Water Column ◽  
Alternative Energy Sources ◽  
Column System ◽  
Ocean Wave Energy ◽  
Wave Conversion

<p>Referring to Law Number 30 of 2007 concerning Energy, the development of techniques the conversion of electrical energy by using alternative energy sources is interesting for followed for the past few years. This paper discusses calculation analysis power potential of ocean wave conversion using the Oscilating Water system Column (OWC) in the marine area of Indonesia. This system was chosen because it has many advantages compared to other systems and in accordance with the marine and coastal areas of Indonesia. From the calculation of power, the smallest power that can be produced is equal to 348.5838 Watts while the biggest power that can be produced is 623291.4 Watts The application of the oscillating water column system in Kendari waters with an efficiency of 11.971%.<br />Keywords. oscillating water column (OWC), ocean wave energy, electrical energy, power potential,<br />wavelength</p>

scholarly journals Double Fed Induction Generator Control Design Based on a Fuzzy Logic Controller for an Oscillating Water Column System

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3499
Author(s):  
Cristian Napole ◽  
Oscar Barambones ◽  
Mohamed Derbeli ◽  
José Antonio Cortajarena ◽  
Isidro Calvo ◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Water Column ◽  
Fuzzy Logic Controller ◽  
Weather Conditions ◽  
Electrical Energy ◽  
Chamber Pressure ◽  
Induction Generator ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Turbine Speed

Oscillating water column (OWC) systems are water power generation plants that transform wave kinetic energy into electrical energy by a surrounded air column in a chamber that changes its pressure through the waves motion. The chamber pressure output spins a Wells turbine that is linked to a doubly fed induction generator (DFIG), flexible devices that adjust the turbine speed to increase the efficiency. However, there are different nonlinearities associated with these systems such as weather conditions, uncertainties, and turbine stalling phenomenon. In this research, a fuzzy logic controller (FLC) combined with an airflow reference generator (ARG) was designed and validated in a simulation environment to display the efficiency enhancement of an OWC system by the regulation of the turbine speed. Results show that the proposed framework not only increased the system output power, but the stalling is also avoided under different pressure profiles.

scholarly journals Three-Dimensional Numerical Simulations of Twisted Stacked Tape Cables

2015 ◽  
Vol 25 (3) ◽  
pp. 1-5 ◽  
Author(s):  
Philipp A. C. Kruger ◽  
Victor M. R. Zermeno ◽  
Makoto Takayasu ◽  
Francesco Grilli
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional

Automatic Three-Dimensional Optimisation of a Modern Tandem Compressor Vane

2014 ◽  
Author(s):  
R. C. Schlaps ◽  
S. Shahpar ◽  
V. Gümmer
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Trust Region ◽  
Automatic Generation ◽  
Navier Stokes ◽  
Design Parameters ◽  
High Fidelity ◽  
Stall Margin ◽  
Design Choice ◽  
Multipoint Approximation

In order to increase the performance of a modern gas turbine, compressors are required to provide higher pressure ratio and avoid incurring higher losses. The tandem aerofoil has the potential to achieve a higher blade loading in combination with lower losses compared to single vanes. The main reason for this is due to the fact that a new boundary layer is generated on the second blade surface and the turning can be achieved with smaller separation occurring. The lift split between the two vanes with respect to the overall turning is an important design choice. In this paper an automated three-dimensional optimisation of a highly loaded compressor stator is presented. For optimisation a novel methodology based on the Multipoint Approximation Method (MAM) is used. MAM makes use of an automatic design of experiments, response surface modelling and a trust region to represent the design space. The CFD solutions are obtained with the high-fidelity 3D Navier-Stokes solver HYDRA. In order to increase the stage performance the 3D shape of the tandem vane is modified changing both the front and rear aerofoils. Moreover the relative location of the two aerofoils is controlled modifying the axial and tangential relative positions. It is shown that the novel optimisation methodology is able to cope with a large number of design parameters and produce designs which performs better than its single vane counterpart in terms of efficiency and numerical stall margin. One of the key challenges in producing an automatic optimisation process has been the automatic generation of high-fidelity computational meshes. The multi block-structured, high-fidelity meshing tool PADRAM is enhanced to cope with the tandem blade topologies. The wakes of each aerofoil is properly resolved and the interaction and the mixing of the front aerofoil wake and the second tandem vane are adequately resolved.

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