Implementação de uma malha dinâmica para estudo da formação da esteira em um aerogerador utilizando simulação de grandes turbilhões

Abstract

The moving air, when passing by a wind turbine is deformed by the blades, generating a turbulent wake its downstream. In this region the speed of the air decreases its magnitude, causing in a reduction of the production of electric energy for other wind turbines located in that area. Another malignant arising from the wake is that there is increased turbulence, producing high fluctuation loads, compromising the propellers’ life. In this way, this work is based on generating a dynamic mesh through of the computational fluid dynamics, for the implementation of a wind turbine, so that analyzes of the characteristics of the turbulent wake region are possible to be obtained. The numerical simulation is performed through the computational fluid dynamics software OpenFoam 2.4.0, through the transient solver pimpleDyMFoam, using as model of turbulence the large eddy simulation. The wind turbine model is generated through the Solid Works software, which has tower height and propeller diameter, 0.213 m and 0.2108 m, respectively. In order to calculate the numerical simulation, the speed of rotation of the blades is set at 9.95 rad/s, having a flow velocity of 1 m/s, through a pressure gradient configured in the initial conditions, and the periodic condition for the and side surfaces, with the non-slip condition applying only to the lower and upper faces. Data are collected in 5 locations in the computational domain, with one upstream and the other four downstream of the wind turbine, which have 23 equally spaced vertical dots. After the equations are discretized, non-dimensional graphs of the velocity, turbulence intensity and Reynolds voltage profiles were generated. When plotting the velocity profiles, we notice a greater velocity drop at the point closest to the downstream, with a greater loss of blade height, where velocity later on tends to resume the magnitude of the velocity as it distances . By analyzing the profiles of the turbulent intensity, a large increase of this is generated just behind the wind turbine, which is due to the tips of the blades, whose movement generates vortices, thus intensifying the creation of turbulence. As this increase in intensity is analyzed, when the Reynolds voltage is checked, negative momentum flux is generated at the blade height, due to the increase shown previously, where it can be seen an increase also, even if with less intensity, in the region of the tower. In view of the presented results, these are in agreement with characteristics of the mat present in the literature, being able in this way to reproduce successfully these effects, making possible the collection of future studies.