Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
An experimental study on ground influence at horizontal axis turbines
Submission Author:
Guilherme Medeiros , DF
Co-Authors:
Guilherme Medeiros, Reginaldo Nunes da Silva, Rafael Castilho Faria Mendes, Taygoara Oliveira, Antonio Brasil Junior
Presenter: Guilherme Medeiros
doi://10.26678/ABCM.COBEM2021.COB2021-2246
Abstract
In turbulent horizontal axis turbine flows, it is necessary to understand the influence of the terrain on the generation of flow structures, where ground roughness is a crucial variable in rotor efficiency, such as hydrokinetic turbines placed in shallow rivers. Thus, this work presents an experimental study on the influence of the ground on the wake close to the horizontal axis turbines, seeking to describe the rotor mat, which is characterized by a complex system of coupled vortices, with high heterogeneity and turbulence instability. The wind tunnel experiments were carried out on a 1.2x1.2 m test section for a 4-blade horizontal axis turbine based on the NACA4412 profile with a diameter of 230 mm. Hot-wire anemometry was used to measure the mean longitudinal velocity profile for two experimental setups, with and without roughness. Wakes regions with high vorticity were identified the helical tip vortex signatures were identified where it is more intense at the height of the upper tip of the blade for both cases. It was also observed that roughness influences the energy available at rotor frequencies because with roughness the energy is presented in F/Ft=1, which shows that roughness accelerates the recovery of the turbine wake.
Keywords
Near-wake, HAWT, Turbulence, Hotwire anemometry, Roughness
