The Experts below are selected from a list of 1098 Experts worldwide ranked by ideXlab platform

Schepers G. - One of the best experts on this subject based on the ideXlab platform.

  • Validation of the Beddoes-Leishman Dynamic Stall Model for Horizontal Axis Wind Turbines using MEXICO data
    American Institute of Aeronautics and Astronautics (AIAA), 2011
    Co-Authors: Pereira R., Schepers G.
    Abstract:

    The aim of this study is to assess the load predicting capability of a classical Beddoes-Leishman dynamic stall model in a horizontal axis wind turbine (HAWT) environment, in the presence of yaw-misalignment. The dynamic stall model was tailored to the HAWT environment, and validated against unsteady Thick Airfoil data. Subsequently, the dynamic stall model was implemented in a blade element-momentum (BEM) code for yawed flow, and the results were compared with aerodynamic measurements obtained in the MEXICO (Model Rotor Experiments under Controlled Conditions ) project on a wind turbine rotor placed in a large scale wind tunnel. In general, reasonable to good agreement was found between the BEM model and MEXICO data. When large yawmisalignments were imposed, poor agreement was found in the downstroke of the movement between the model and the experiment. Still, over a revolution the maximum normal force coefficient predicted was always within 8% of experimental data at the inboard stations, which is encouraging especially when blade fatigue calculations are being considered

  • Validation of the Beddoes-Leishman Dynamic Stall Model for Horizontal Axis Wind Turbines using MEXICO data
    'American Institute of Aeronautics and Astronautics (AIAA)', 2011
    Co-Authors: Pereira R., Schepers G.
    Abstract:

    The aim of this study is to assess the load predicting capability of a classical Beddoes-Leishman dynamic stall model in a horizontal axis wind turbine (HAWT) environment, in the presence of yaw-misalignment. The dynamic stall model was tailored to the HAWT environment, and validated against unsteady Thick Airfoil data. Subsequently, the dynamic stall model was implemented in a blade element-momentum (BEM) code for yawed flow, and the results were compared with aerodynamic measurements obtained in the MEXICO (Model Rotor Experiments under Controlled Conditions ) project on a wind turbine rotor placed in a large scale wind tunnel. In general, reasonable to good agreement was found between the BEM model and MEXICO data. When large yawmisalignments were imposed, poor agreement was found in the downstroke of the movement between the model and the experiment. Still, over a revolution the maximum normal force coefficient predicted was always within 8% of experimental data at the inboard stations, which is encouraging especially when blade fatigue calculations are being considered.Control & OperationsAerospace Engineerin

Kelso R. - One of the best experts on this subject based on the ideXlab platform.

  • Lift curve breakdown for Airfoil undergoing dynamic stall
    Australasian Fluid Mechanics Society, 2014
    Co-Authors: Choudhry A., Arjomandi M., Kelso R.
    Abstract:

    The work presented aims to investigate the lift-characteristics of a Thick Airfoil section undergoing dynamic stall. The NACA 0021 Airfoil was selected for the experimental work performed at the KC Wind Tunnel at the University of Adelaide. The Airfoil was pitched at the mid-chord and the unsteady surface pressure distributions were recorded. The surface pressures were then used to obtain the lift-curve for the Airfoil undergoing dynamic stall. In the present article, the unsteady lift-curve has been broken down into stages and each stage has been analysed to gain a deeper understanding of the dynamic stall lift.A. Choudhry, M. Arjomandi, and R. Kels

G J W Van Bussel - One of the best experts on this subject based on the ideXlab platform.

  • experimental parameter study for passive vortex generators on a 30 Thick Airfoil
    Wind Energy, 2018
    Co-Authors: Daniel Baldacchino, Carlos Simao Ferreira, Delphine De Tavernier, W A Timmer, G J W Van Bussel
    Abstract:

    Passive vane-type vortex generators (VGs) are commonly used on wind turbine blades to mitigate the effects of flow separation. However, significant uncertainty surrounds VG design guidelines. Understanding the influence of VG parameters on Airfoil performance requires a systematic approach targeting wind energy-specific Airfoils. Thus, the 30%-Thick DU97-W-300 Airfoil was equipped with numerous VG designs, and its performance was evaluated in the Delft University Low Turbulence Wind Tunnel at a chord-based Reynolds number of 2×106. Oil-flow visualizations confirmed the suppression of separation as a result of the vortex-induced mixing. Further investigation of the oil streaks demonstrated a method to determine the vortex strength. The Airfoil performance sensitivity to 41 different VG designs was explored by analysing model and wake pressures. The chordwise positioning, array configuration, and vane height were of prime importance. The sensitivity to vane length, inclination angle, vane shape, and array packing density proved secondary. The VGs were also able to delay stall with simulated Airfoil surface roughness. The use of the VG mounting strip was detrimental to the Airfoil's performance, highlighting the aerodynamic cost of the commonly used mounting technique. Time-averaged pressure distributions and the lift standard deviation revealed that the presence of VGs increases load fluctuations in the stalling regime, compared with the uncontrolled case.

Marinos Manolesos - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Study of Drag-Reduction Devices on a Flatback Airfoil
    'American Institute of Aeronautics and Astronautics (AIAA)', 2016
    Co-Authors: Marinos Manolesos
    Abstract:

    Various trailing-edge drag-reduction devices, including a new flap device, were examined experimentally on a flatback Airfoil in a wind tunnel. The tests concerned a 30% Thick Airfoil with 10.6% Thick trailing edge. Pressure, hot wire, and stereo particle image velocimetry measurements were performed at a chord Reynolds number of 1.5e6. Results show that the best-performing devices decrease drag, increase the vortex shedding frequency, and reduce flow variation downstream of the wing trailing edge. The best-performing device was a combination of the flap with an offset cavity plate. Further investigation is required for the optimization of the new device to examine its effects on noise reduction, load mitigation, and control

  • Geometrical characterization of stall cells on rectangular wings
    'Wiley', 2014
    Co-Authors: Marinos Manolesos
    Abstract:

    The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% Thick Airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been known for long, neither are their characteristics completely documented nor their generating mechanisms fully understood. The present investigation aims at providing additional information on the geometric characteristics in terms of width, length and occupied area. The relevant data are presented as functions of Reynolds (Re) number, angle of attack and aspect ratio (AR) of the model. In the tests reported, the dynamic character of SCs is suppressed by imposing a localized flow disturbance. For the specific Airfoil and for the Re and AR range tested, it is found that: the angle of attack at which SCs are initially formed decreases linearly with Re number and independently of the AR; unlike two‐dimensional separation, their chordwise length increases with Re; the SC area relative to the wing planform area (defined as the relative SC area) grows asymptotically with angle of attack and Re number reaching an upper bound, which is independent of the AR; at intermediate angles of attack, the SC relative area is higher for the lower AR wing; for a fixed increment in Re number, the growth of the SC relative area is independent of the initial Re number; at lower angles of attack, the actual SC area is independent of the wing span

  • geometrical characterization of stall cells on rectangular wings
    Wind Energy, 2013
    Co-Authors: Marinos Manolesos, Spyros G Voutsinas
    Abstract:

    The onset of stall cells (SCs) is experimentally investigated on a flattop loaded 18% Thick Airfoil optimized for use on wind turbine blades, exhibiting trailing edge separation. SCs are dynamic coherent vortical structures that appear on wings under separated flow conditions. Although SCs have been known for long, neither are their characteristics completely documented nor their generating mechanisms fully understood. The present investigation aims at providing additional information on the geometric characteristics in terms of width, length and occupied area. The relevant data are presented as functions of Reynolds (Re) number, angle of attack and aspect ratio (AR) of the model. In the tests reported, the dynamic character of SCs is suppressed by imposing a localized flow disturbance. For the specific Airfoil and for the Re and AR range tested, it is found that: the angle of attack at which SCs are initially formed decreases linearly with Re number and independently of the AR; unlike two-dimensional separation, their chordwise length increases with Re; the SC area relative to the wing planform area (defined as the relative SC area) grows asymptotically with angle of attack and Re number reaching an upper bound, which is independent of the AR; at intermediate angles of attack, the SC relative area is higher for the lower AR wing; for a fixed increment in Re number, the growth of the SC relative area is independent of the initial Re number; at lower angles of attack, the actual SC area is independent of the wing span. Copyright © 2013 John Wiley & Sons, Ltd.

Pereira R. - One of the best experts on this subject based on the ideXlab platform.

  • Validation of the Beddoes-Leishman Dynamic Stall Model for Horizontal Axis Wind Turbines using MEXICO data
    American Institute of Aeronautics and Astronautics (AIAA), 2011
    Co-Authors: Pereira R., Schepers G.
    Abstract:

    The aim of this study is to assess the load predicting capability of a classical Beddoes-Leishman dynamic stall model in a horizontal axis wind turbine (HAWT) environment, in the presence of yaw-misalignment. The dynamic stall model was tailored to the HAWT environment, and validated against unsteady Thick Airfoil data. Subsequently, the dynamic stall model was implemented in a blade element-momentum (BEM) code for yawed flow, and the results were compared with aerodynamic measurements obtained in the MEXICO (Model Rotor Experiments under Controlled Conditions ) project on a wind turbine rotor placed in a large scale wind tunnel. In general, reasonable to good agreement was found between the BEM model and MEXICO data. When large yawmisalignments were imposed, poor agreement was found in the downstroke of the movement between the model and the experiment. Still, over a revolution the maximum normal force coefficient predicted was always within 8% of experimental data at the inboard stations, which is encouraging especially when blade fatigue calculations are being considered

  • Validation of the Beddoes-Leishman Dynamic Stall Model for Horizontal Axis Wind Turbines using MEXICO data
    'American Institute of Aeronautics and Astronautics (AIAA)', 2011
    Co-Authors: Pereira R., Schepers G.
    Abstract:

    The aim of this study is to assess the load predicting capability of a classical Beddoes-Leishman dynamic stall model in a horizontal axis wind turbine (HAWT) environment, in the presence of yaw-misalignment. The dynamic stall model was tailored to the HAWT environment, and validated against unsteady Thick Airfoil data. Subsequently, the dynamic stall model was implemented in a blade element-momentum (BEM) code for yawed flow, and the results were compared with aerodynamic measurements obtained in the MEXICO (Model Rotor Experiments under Controlled Conditions ) project on a wind turbine rotor placed in a large scale wind tunnel. In general, reasonable to good agreement was found between the BEM model and MEXICO data. When large yawmisalignments were imposed, poor agreement was found in the downstroke of the movement between the model and the experiment. Still, over a revolution the maximum normal force coefficient predicted was always within 8% of experimental data at the inboard stations, which is encouraging especially when blade fatigue calculations are being considered.Control & OperationsAerospace Engineerin