Rotor Blade Airflow Modifiers for Standstill Vibration Mitigation
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Solution Overview
Problem
Wind turbines experience damaging vortex-shedding and stall-induced vibrations during standstill due to wind flow, which existing methods struggle to mitigate effectively, especially when rotor blade adjustments are not possible.
Innovation Solution
An apparatus comprising a positioning element wrapped around the rotor blade with airflow modifying elements, such as streamers, fences, or inflatable cells, secured by a cord or sleeve to disrupt airflow and prevent vortex formation, thereby reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor blade position is fixed during maintenance, then safety is improved, but the inability to adjust pitch or yaw exposes the blade to flow-induced oscillations
Solution Approach 1:
The flow control elements are designed to be self-activating or self-regulating during maintenance operations. For example, passive flow control devices such as Gurney flaps or vortex generators are permanently installed on the blade and automatically function to control flow separation and reduce vibrations without requiring active control systems or operator intervention. This allows the blade to protect itself from flow-induced oscillations while fixed in position during maintenance.
Solution Approach 2:
Flow control elements are pre-installed and pre-configured on the rotor blade before maintenance operations begin. These elements (such as leading-edge extensions, trailing-edge flaps, or surface roughness elements) are positioned in advance to optimize flow attachment for the expected range of wind conditions during maintenance. This preliminary preparation ensures that when the blade is fixed in position, the flow control elements are already in place to mitigate vibrations without requiring adjustment during the maintenance window.
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 apparatus effectively mitigates vortex-shedding and stall-induced vibrations by disrupting airflow and preventing vortex formation, reducing the likelihood of damaging oscillations during maintenance or idling conditions.
Implementation Method 1
the wind attempts to flow around the slender structure of the rotor blade and form a vortex at the point where the flow separates from the rotor blade. Depending on the relative angle between the wind and the rotor blade, a vortex-shedding phenomenon may occur where the vortices form on the edges of the blade and are shed in a rhythmic pattern
Implementation Method 2
at least one positioning element located between a blade tip section and a blade root section thereof. The positioning element(s) is adapted for wrapping around at least a portion of the rotor blade
Data Source
AI summary
An apparatus for mitigating vortex-shedding vibrations or stall-induced vibrations on one or more rotor blades of a wind turbine during standstill includes at least one positioning element located between a blade tip section and a blade root section thereof. The positioning element is adapted for wrapping around at least a portion of the rotor blade. The apparatus also includes at least one airflow modifying element coupled to the positioning element and defining a height relative to a surface of the rotor blade. Additionally, the apparatus includes at least one securing element operably coupled to the positioning element for temporarily securing the airflow modifying element to the rotor blade.