Author: Charles P. ButterfieldPublisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 0
Book Description
Recent Results from Data Analysis of Dynamic Stall on Wind Turbine Blades
Author: Charles P. ButterfieldPublisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 0
Book Description
Recent Results from Data Analysis of Dynamic Stall on Wind Turbine Blades
Author: Charles P. ButterfieldPublisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 13
Book Description
Modeling Dynamic Stall on Wind Turbine Blades Under Rotationally Augmented Flow Fields
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 28
Book Description
It is well known that airfoils under unsteady flow conditions with a periodically varying angle of attack exhibit aerodynamic characteristics different from those under steady flow conditions, a phenomenon commonly known as dynamic stall. It is also well known that the steady aerodynamic characteristics of airfoils in the inboard region of a rotating blade differ from those under steady two-dimensional (2D) flow conditions, a phenomenon commonly known as rotational augmentation. This paper presents an investigation of these two phenomena together in the inboard parts of wind turbine blades. This analysis is carried out using data from three sources: (1) the National Renewable Energy Laboratory's Unsteady Aerodynamics Experiment Phase VI experimental data, including constant as well as continuously pitching blade conditions during axial operation, (2) data from unsteady Delayed Detached Eddy Simulations (DDES) carried out using the Technical University of Denmark's in-house flow solver Ellipsys3D, and (3) data from a simplified model based on the blade element momentum method with a dynamic stall subroutine that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional 2D nonrotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared to three select cases of the N sequence experimental data, which serves as a validation of the DDES method. Results show reasonable agreement between the two data in two out of three cases studied. Second, the dynamic time series of the lift and the moment polars obtained from the experiments are compared to those from the dynamic stall subroutine that uses the rotationally augmented steady polars. This allowed the differences between the stall phenomenon on the inboard parts of harmonically pitching blades on a rotating wind turbine and the classic dynamic stall representation in 2D flow to be investigated. Results from the dynamic stall subroutine indicated a good qualitative agreement between the model and the experimental data in many cases, which suggests that the current 2D dynamic stall model as used in BEM-based aeroelastic codes may provide a reasonably accurate representation of three-dimensional rotor aerodynamics when used in combination with a robust rotational augmentation model.
Scientific and Technical Aerospace Reports
Author: Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 602
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Dynamic Stall on Wind Turbine Blades
Author: Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 0
Book Description
Dynamic loads must be predicted accurately in order to estimate the fatigue life of wind turbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis wind turbines (HAWTs). This reports illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operatingconditions. Lift, drag, and pitching moment coefficients during dynamic stall are discussed. Resulting dynamic loads are presented, and the effects of dynamic stall on yaw loads are demonstrated using a yaw loads dynamic analysis (YAWDYN).
Energy Research Abstracts
Author: Zinnenverzinzin Kinderboekenweek 2008
Author: Dynamic Stall Occurrence on a Horizontal Axis Wind Turbine Blade
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
Surface pressure data from the National Renewable Energy Laboratory's ''Combined Experiment'' were analyzed to provide a statistical representation of dynamic stall occurrence on a downwind horizontal axis wind turbine (HAWT). Over twenty thousand blade rotational cycles were each characterized at four span locations by the maximum leading edge suction pressure and by the azimuth, velocity, and yaw at which it occurred. Peak suction values at least twice that seen in static wind tunnel tests were taken to be indicative of dynamic stall. The occurrence of dynamic stall at all but the inboard station (30% span) shows good quantitative agreement with the theoretical limits on inflow velocity and yaw that should yield dynamic stall. Two hypotheses were developed to explain the discrepancy at 30% span. Estimates are also given for the frequency of dynamic stall occurrence on upwind turbines. Operational regimes were identified which minimize the occurrence of dynamic stall events.
Author: 
Author: