COMPORTAMIENTO DEL FLUJO EN LA ESTELA DEL PERFIL NREL S830 PARA TURBINA EÓLICA

Abstract

The near wake behavior and the development of velocity and turbulence intensity profiles in the wake of a NREL S830 blade are investigated. This study was made for a Re interval of 190 000 – 450 000, varying the blade´s attack angle between 0° and 17° and taking into account the influence of 0.5% and 10% FST levels. By means of the flow visualization smoke tracer and tuft-grid techniques the nature of the flow in the near wake can be qualitatively described The smoke tracer objective is to determine the limit of the blade´s tip influence area (tip vortex) on the flow field, mainly in the spanwise axis direction (z axis). The tuft-grid on the other hand is used to mark the characteristics of the tip vortex zone in the blade’s wake and also to locate the deviant flow region in the normal axis direction (y axis). A hot wire anemometry equipment (HWA) was used to obtain the velocity measurements of the streamwise direction of the flow (x axis) and thus its profiles, with the acquired velocity data the turbulent intensity profiles are calculated. The sampling frequency and time used for this experimental work is 20 kHz and 15 s respectively. Maps on the evolution of the streamwise velocity and turbulence intensity profiles are obtained. The results characterize the behavior of the wake in five different measurement planes: 0.2C, 0.5C, 3C, 4C y 5C. It is also possible for Re ≥ 250 000 to locate the maximum velocity and turbulence intensity restitution zone in the far wake (self similarity condition). The results are compared with studies made to other airfoils in similar experimental conditions of the ones present in this thesis work. Is finally concluded that the NREL S830 blade for wind turbine applications has a better wake behavior compared to those existent in the state of the art.