Optimal blade pitch control for enhanced vertical-axis wind turbine performance

Area of Science:

• Renewable Energy
• Aerodynamics
• Fluid Dynamics

Background:

• Vertical-axis wind turbines (VAWTs) show promise for urban and offshore wind power.
• Current VAWT designs face limitations in efficiency and structural integrity.
• Flow control strategies are crucial for mitigating these limitations.

Purpose of the Study:

• To experimentally demonstrate individual blade pitching as an effective flow control strategy for VAWTs.
• To identify optimal pitching kinematics for enhanced performance and structural integrity.
• To elucidate the underlying flow physics responsible for performance improvements.

Main Methods:

• Automated experiments using a scaled-down VAWT model.
• Optimization using a genetic algorithm to determine optimal pitching kinematics.
• Flow field measurements to analyze flow structures and control mechanisms.

Main Results:

• Optimal pitch profiles achieved a threefold increase in power coefficient at both on- and off-design conditions.
• A 77% reduction in structure-threatening load fluctuations was observed at off-design conditions.
• Blade pitching was shown to manipulate flow structures for performance enhancement.

Conclusions:

• Individual blade pitching is a highly effective flow control strategy for VAWTs.
• This method significantly improves energy extraction efficiency and operational stability.
• The findings support the increased contribution of VAWTs to renewable energy demands.