Evidence That Aerodynamic Effects, Including Dynamic Stall, Dictate HAWT Structure Loads and Power Generation in Highly Transient Time Frames
Aerodynamic data collected from the National Renewable Energy Laboratory`s Combined Experiment have shown three distinct performance regimes when the turbine is operated under relatively steady flow conditions. Operating at blade angles of attack below static stall, excellent agreement is achieved with two-dimensional wind tunnel data. Around the static stall angle, the cycle average normal force produced is greater than the static test data. Span locations near the hub produce extremely large values of normal force coefficient, well in excess of the two-dimensional data results. These performance regimes have been shown to be a function of the three-dimensional flow structure and cycle averaged dynamic stall effects. Power generation and root bending moments have also been shown to be directly dependent on the inflow wind velocity. Aerodynamic data, including episodes of dynamic stall, have been correlated on a cycle by cycle basis with the structural and power generation characteristics of a horizontal axis wind turbine. Instantaneous unsteady forces and resultant power generation indicate that peak transient levels can significantly exceed cycle averaged values. Strong coupling between transient aerodynamic and resonant response of the turbine was also observed. These results provide some initial insight into the contribution of unsteady aerodynamics on undesirable turbine structural response and fatigue life.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 10177826
- Report Number(s):
- NREL/TP-441-7080; ON: DE94011865; BR: WM1020000
- Resource Relation:
- Conference: WINDPOWER `94: American Wind Energy Association (AWEA) annual conference and exhibition,Minneapolis, MN (United States),9-13 May 1994; Other Information: PBD: Aug 1994
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mesh and model requirements for capturing deep-stall aerodynamics in low-Mach-number flows
New vortex‐lift and tangential‐force models for HAWT aerodynamic load prediction