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This paper sets out to describe the measurements and computations to construct three components of velocity field around the blade. The primary aim of the measurements was to gain insight into the physics of the flow field produced by a horizontal axis wind turbine-HAWT blade. Stereo Particle Image Velocimetry experiments were performed on a two-bladed HAWT rotor in the open jet facility. Three components of velocity on 2D planar measurement planes were obtained from the defined field of views. The three components of velocity at the different radial positions are analysed in the present paper by comparing the experimental results with the panel code results. Besides having an insight about the flow field around the blade section, this comparison enables to improve and validate the panel code. The measurements show very well agreement with the computations except at the tip trailing edge region which is expected. The key observation of this work is inboard motion of the tip vortex. Also, clear outward motion of the radial flow on the suction side of the inboard sections of the blade is observed in the measurements and computations.

This paper explores the evolution of radial flow in a Horizontal Axis Wind Turbine (HAWT) blade root region. The radial flow is analyzed in the potential flow and viscous flow regions. An experiment carried out by means of stereo Particle Image Velocimetry to measure the velocity field produced by a HAWT blade. While the radial flow in the potential flow region was obtained from the measurements, the radial flow in the boundary layer was derived from CFD. By the direct observations obtained from the experiment, an insight is gained about the nature of the radial flow in the suction side of the blade as well as in the near wake. An outboard radial flow motion is observed in the root region. This tendency of the flow changes dramatically when it reaches the maximum chord position of the blade, where the radial flow moves inboard. The trace of the viscous region due to merging of the boundary layers and trailing vorticity are observed clearly in the radial velocity and vorticity distributions at 135º azimuth angle of the blade. In the viscous flow region the radial flow is more pronounced than in the potential flow region. The performed CFD simulations are able to predict the vortex formation in the maximum chord region and its interaction with the nacelle.

A detailed quantitative description of the aerodynamics of a horizontal axis wind turbine (HAWT) is difficult due to complexity of the flow field. Several methods from experimental to analytical are used to investigate the aerodynamics of a HAWT. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulations are used to explore the expansion of the wake. 2D actuator disc (AD) simulations are compared with the wind tunnel experiments. To understand the aerodynamic behavior of a model wind turbine blade, a detail flow field measurements in chordwise-spanwise directions and in the wake have been done. The measurements are performed on a 2 bladed rotor by means of Stereo Particle Image Velocimetry (Stereo PIV) in an open jet wind tunnel. In this paper, the velocity measurements performed in the wake region of the blade is presented. Actuator disc simulations are performed by applying a constant pressure jump on a permeable disc of zero thickness. Actuator disc simulations are carried out by using FLUENT 6.3.26 with the incompressible version of the Reynolds Averaged Navier-Stokes (RANS) equations. By validating the simulations with the experimental results, one may conclude that the unsteady CFD modeling works correctly and the wake expansion of the prescribed model is affected by the geometry of the Open Jet Facility (OJF).

The scope of this work was to investigate radial flow component for a Horizontal Axis Wind Turbine in axial flow conditions and to assess its impact on the turbine operation. This was done by means of Particle Image Velocimetry and numerical simulation with a 3D unsteady potential-flow panel model. A direct comparison between the numerical and experimental radial velocity results show differences in the tip and root regions. These differences have important implications on the wake development just at the moment of release of the tip vortex. Moreover, the impact of the radial velocities on the blade loading has been studied using the numerical results. The contribution of the radial velocity to the normal load on the blade is only slightly appreciable in the tip and root regions of the blade. However, as the numerical model does not account for viscous effects, further analysis of impact on boundary layer development is necessary.