Wind Turbine Active Flap With Secondary Body for Neutral Stability
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Solution Overview
Problem
Prior art active flaps on wind turbine rotor blades are unable to maintain a neutral position due to unintentional deflection by airflow, leading to unintended lift increases and reduced effectiveness in load management.
Innovation Solution
An active flap with a secondary body that guides airflow to maintain a neutral position, using an inflatable chamber and flap turning means to ensure the flap remains in a low-lift configuration, and a secondary body with convex or auxiliary airfoil shapes to counteract airflow forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prior art active flap is used to guide airflow over the rotor blade, then lift can be increased when needed, but the flap cannot maintain its neutral position due to unintentional deflection by airflow, causing unintended lift increase
Solution Approach 1:
A secondary body is introduced as an intermediary aerodynamic surface between the airflow and the active flap. This secondary body guides the airflow in such a way that it prevents the airflow from unintentionally deflecting the active flap from its neutral position, thereby maintaining position stability without interfering with the flap's intended aerodynamic function
Solution Approach 2:
The secondary body is designed to counteract the harmful airflow forces before they can deflect the active flap. By positioning the secondary body upstream and shaping it to guide airflow, it creates a protective aerodynamic environment that prevents the unintended deflection from occurring in the first place
2Force
If the active flap is turned to neutral position to reduce lift during high wind conditions, then load on rotor blade is reduced, but the flap is unintentionally turned out of neutral position by airflow forces, reducing effectiveness of load management
Solution Approach 1:
The secondary body acts as a mediator that shields the active flap from destabilizing airflow forces. It guides the airflow smoothly over the rotor blade surface, preventing turbulent or accelerating flows from acting directly on the active flap and causing position instability
Solution Approach 2:
The secondary body creates counteracting aerodynamic forces that balance the destabilizing forces on the active flap. By shaping the secondary body to generate favorable pressure distributions, it creates aerodynamic counterweights that hold the active flap in its intended neutral position
3Productivity
If the active flap geometry causes local acceleration of airflow, then aerodynamic performance is enhanced, but unintended pressure forces are generated that deflect the flap towards pressure side
Solution Approach 1:
The aerodynamic surface is segmented into two distinct functional parts: the active flap for primary aerodynamic control and the secondary body for airflow guidance. This segmentation allows the secondary body to manage the airflow in a way that prevents harmful pressure forces from developing on the active flap, while the active flap maintains its aerodynamic effectiveness
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 active flap effectively maintains its neutral position, allowing precise control over lift forces, reducing loads during gusty conditions and enabling optimal power output in varying wind conditions.
Implementation Method 1
the secondary body guides the airflow over the rotor blade in such a way that the active flap is not passively—i.e. unintentionally-turned out of its neutral position
Implementation Method 2
using an inflatable chamber and flap turning means to ensure the flap remains in a low-lift configuration
Data Source
AI summary
The invention describes a wind turbine rotor blade active flap (1) comprising a primary body (1P) adapted for mounting to the trailing edge (20TE) of a wind turbine rotor blade (20); a flap turning means (10, 11, 12) adapted to turn the active flap (1) between a neutral position (R0), in which the active flap (1) directs airflow (A20S, A20P) towards the suction side (P20S) of the rotor blade (20), and a working position (R-Rmax), in which the active flap (1) directs airflow (A20S, A20P) towards the pressure side (P20P) of the rotor blade (20); and a secondary body (1S) mounted to the primary body (1P) and configured to hold the active flap (1) in its neutral position (R0). The invention further describes a wind turbine (2) comprising a number of rotor blades (20) mounted to a hub; and an active flap (1) according to the invention, mounted to the trailing edge (20TE) of each rotor blade (20).