A critical examination of the hysteresis in wells turbines using computational fluid dynamics and lumped parameter models

Ghisu T.
;
Cambuli F.;Puddu P.;Virdis I.;Carta M.;Licheri F.
2020-01-01

Abstract

The hysteretic behavior of oscillating water column (OWC)-installed Wells turbines has been known for decades. The common explanation invokes the presence of unsteady aerodynamics due to the continuously varying incidence of the flow on the turbine blades. This phenomenon is neither new nor unique to Wells turbines, as an aerodynamic hysteresis is present in rapidly oscillating airfoils and wings, as well as in different types of turbomachinery, such as wind turbines and helicopter rotors, which share significant similarities with a Wells turbine. An important difference is the non-dimensional frequency: the hysteresis appears in oscillating airfoils only at frequencies orders of magnitude larger than the ones Wells turbines operate at. This work contains a re-examination of the phenomenon, using both computational fluid dynamics (CFD) and a lumped parameter model, and shows how the aerodynamic hysteresis in Wells turbines is negligible and how the often measured differences in performance between acceleration and deceleration are caused by the capacitive behavior of the OWC system. Results have been verified with respect to both spatial and temporal discretization, for unstalled and stalled operating conditions.
2020
computational fluid dynamics; ocean wave energy technology; lumped parameter model; verification and validation; Wells turbines
Files in This Item:
File Size Format  
TGhisu_J26.pdf

Solo gestori archivio

Description: articolo online
Type: versione editoriale
Size 1.9 MB
Format Adobe PDF
1.9 MB Adobe PDF & nbsp; View / Open   Request a copy

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Questionnaire and social

Share on:
Impostazioni cookie