Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
NUMERICAL ANALYSIS OF A SAVONIUS TURBINE INSERTED IN OSCILLATING WATER COLUMN WAVE ENERGY CONVERTER
Submission Author:
Andrei Santos , RS
Co-Authors:
Andrei Santos, Filipe Branco Teixeira, Liércio Isoldi, jeferson Avila Souza, Mateus das Neves Gomes, Luiz Alberto Oliveira Rocha, Elizaldo dos Santos
Presenter: Andrei Santos
doi://10.26678/ABCM.COBEM2021.COB2021-0265
Abstract
This work presents a numerical analysis of a turbulent flow over a Savonius turbine in a domain that mimics an Oscillating Water Column (OWC) device. The model includes a dynamic mesh simulation on which the turbine angular velocity is prescribed. The geometry is investigated using Constructal Design, being considered a constant area (A1) for the chamber and two degrees of freedom. Here, the effect of the turbine duct positioning on the equipment, represented by the ratio between the distance from the position of the water-free surface to the turbine duct center and the height of the OWC device (H2/H1), on the resulting power coefficient is evaluated. For all cases, the height/length ratio of the chamber is constant (H1/L1 = 0.55). The study is carried out considering a two-dimensional domain, where the OWC device contains the turbine duct on the side of its chamber. The airflow in the domain is caused by the imposition of a constant velocity Vcte = 1.4 m/s at the lower surface of the OWC chamber. Moreover, a turbine rotor constant velocity ω’ = 15.5 rad/s is imposed in the Savonius turbine. The computational mesh was generated with the GMSH software. To solve the turbulent flow, the time averaged equations of mass conservation and balance of momentum are solved numerically with the finite volume method (FVM), more precisely with the Ansys Fluent 18.1 commercial software. For closure of turbulence, it is considered the k –ω SST Reynolds-Averaged Navier Stokes (RANS) method. A comparison between present method and results of literature for a case with free Savonius turbine was performed to verify the solution. The studied cases of OWC with turbine were also compared with similar domains and without inserted turbine with the aim to investigate the influence of the model simplification in the performance and design of the device. For the present conditions, the highest power take off (PTO) on the device and available power were obtained for the highest magnitude of the ratio H2/H1 (H2/H1 = 0.81). Moreover, the effect of the ratio H2/H1 over the PTO and available power for the conditions with and without turbine were similar, indicating that the improvement of the model (considering the turbine) was important only for prediction of PTO and not for the recommendation about the best configuration of the device.
Keywords
OWC, Numerical simulation, Savonius turbine, turbulent flows, Constructal Design
