Rotor Blade Leading-Edge Protrusions for Stall Vibration Mitigation
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Solution Overview
Problem
Wind turbines experience stall-induced vibrations during standstill due to flow-induced oscillations caused by wind impacting the rotor blades at an angle of attack, leading to vortex shedding and potential structural damage.
Innovation Solution
A rotor blade assembly with protrusions secured at the leading or trailing edge, angled relative to the chordwise reference line, designed to disrupt vortex shedding and mitigate vibrations by affecting crosswise airflow patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotor blade is feathered to counteract stall-induced vibrations, then vibrations are reduced, but the ability to capture kinetic energy is lost
Solution Approach 1:
The rotor blade is segmented into multiple functional zones: the main airfoil section for kinetic energy capture, and the protrusion element at the leading edge specifically for vibration mitigation. This segmentation allows each zone to perform its specialized function independently - the protrusion disrupts vortex shedding to reduce vibrations while the main blade profile maintains aerodynamic efficiency for energy capture.
Solution Approach 2:
The protrusion element is strategically positioned only at the leading edge of the rotor blade, creating a localized modification that affects only the flow characteristics at that specific location. This local quality change disrupts the spanwise flow component and vortex formation without altering the overall blade aerodynamics, thereby mitigating vibrations while preserving kinetic energy capture capability.
2Object-affected harmful factors
If protrusions are added to the rotor blade to disrupt vortex shedding, then stall-induced vibrations are reduced, but device complexity increases
Solution Approach 1:
The vibration mitigation function is extracted from the main rotor blade structure and implemented as a separate, modular protrusion element. This extracted component can be independently designed, manufactured, and installed, simplifying the overall system complexity while achieving the desired flow disruption effect. The protrusion is a discrete element rather than a complex integrated system.
Solution Approach 2:
The protrusion element is designed as a simple, easily replaceable component that can be manufactured at low cost. If the protrusion becomes damaged or wears over time, it can be quickly replaced without affecting the main rotor blade structure, reducing maintenance complexity and downtime.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The protrusions effectively minimize drag during normal operation while maximizing their impact on crosswise airflow in stalled conditions, reducing stall-induced vibrations and structural damage.
Implementation Method 1
the wind may form vortices at locations where the flow separates from the rotor blade
Implementation Method 2
where the flow separates from the rotor blade
Data Source
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AI summary
A rotor blade assembly for mitigating stall-induced vibrations of a wind turbine during standstill includes at least one protrusion secured to the leading-edge of a rotor blade and defining an extended leading edge. The protrusion(s) wraps around a portion of the rotor blade from the suction side to the pressure side of the rotor blade. The protrusion(s) has a root-side face and a tip-side face disposed opposite thereof. The root- side face is arranged at an angle relative to a chordwise reference line. The angle is greater than zero degrees and less than or equal to 45 degrees with respect to the chordwise reference line. The protrusion(s) is configured to affect a chordwise airflow and thereby mitigate a stall-induced vibration.