Rotatable Diffuser Ring with Vortex Entrainment for Wind Turbines
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Solution Overview
Problem
Conventional wind turbines are limited by Betz' law, which restricts the conversion of wind kinetic energy to mechanical energy to 59.3%, and existing diffuser augmentations require large, uneconomic cowlings that increase drag and reduce efficiency due to the need for a significant expansion in exit area to accelerate airflow effectively.
Innovation Solution
A diffuser-augmented wind turbine design featuring a rotatable diffuser ring with vortex entrainment devices and slot gaps that create a progressively decreasing duct cross-sectional area, allowing high-pressure air to be injected tangentially, re-energizing the boundary layer and accelerating airflow through the turbine rotor plane, thereby increasing efficiency beyond theoretical limits without the need for bulky cowlings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional diffusers use a large expansion in exit area to accelerate airflow, then wind speed increases, but drag increases and the structure becomes uneconomic
Solution Approach 1:
The diffuser is divided into multiple diffuser rings arranged in series, each with progressively decreasing cross-sectional area. This segmentation allows incremental acceleration of airflow through each stage rather than requiring a single large expansion, reducing overall drag while achieving the same wind speed increase.
Solution Approach 2:
The patent transitions from a conventional single-plane diffuser to a multi-ring three-dimensional structure with progressive area reduction. This dimensional approach creates multiple acceleration zones along the airflow path, enabling efficient speed increase without the drag penalties of a single large expansion.
2Power
If conventional diffusers expand exit area to increase power output, then airflow velocity increases, but the structure becomes bulky and uneconomic
Solution Approach 1:
The diffuser structure is segmented into multiple rings with progressively decreasing cross-sectional areas. This allows the system to achieve the necessary exit area expansion for increased power output while distributing the volume increase across multiple compact stages rather than requiring a single bulky structure.
Solution Approach 2:
The multiple diffuser rings are nested concentrically around the rotor, with each ring positioned within the flow path of the previous ring. This nesting arrangement achieves the required total volume expansion for power increase while maintaining a compact overall structure that doesn't protrude significantly.
3Use of energy by moving object
If Betz' law limits are applied to classical wind turbines, then energy conversion is constrained to 59.3%, but diffuser augmentation can exceed this limit
Solution Approach 1:
The energy conversion process is segmented into multiple stages, with each diffuser ring contributing to incremental acceleration and energy extraction. This multi-stage approach allows the system to exceed Betz' law limits by capturing energy in discrete steps rather than being constrained by single-plane axial flow limitations.
Solution Approach 2:
The diffuser rings are designed to rotate with the rotor, creating dynamic interaction between the rotating structure and the airflow. This dynamic configuration enables the system to extract energy more efficiently than static diffusers, allowing energy conversion to exceed the 59.3% Betz limit while managing structural complexity through rotational symmetry.
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 design enhances wind energy conversion efficiency by accelerating airflow and reducing drag, allowing for increased power output while minimizing the visual and economic impact of the turbine, and can be retrofitted into existing installations.
Implementation Method 1
one or more vortex entrainment devices are arranged on a trailing edge of the diffuser... The vortex entrainment devices create vortices downstream of the diffuser which reduces the pressure behind the turbine rotor plane
Implementation Method 2
one or more slot gaps arranged within its body, each slot gap creating a channel between the interior and exterior surfaces of the first diffuser ring... enabling the injection of higher speed air tangentially or substantially tangential to the internal or lower surface of a diffuser ring by channelling high pressure air
Implementation Method 3
Wind turbine diffusers may be used to increase the velocity of the air entering the turbine's rotor plane... This system decreases the air pressure behind the wind turbine and therefore draws more air through the turbine rotor plane
Data Source
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AI summary
Diffuser-augmented wind turbines are described. In an embodiment a wind turbine diffuser comprises a first diffuser ring arranged to form a turbine rotor cowling, the diffuser being fixed to and rotatable with the turbine rotor about the horizontal axis of the wind turbine. The first diffuser ring may have one or more dynamic, aero-elastic, vortex entrainment devices attached to a trailing edge of the diffuser. The first diffuser ring may comprise one or more slot gaps arranged within its body, each slot gap creating a channel between the interior and exterior surfaces of the first diffuser ring. In some embodiments the diffuser may optionally further comprise one or more further diffuser rings, the one or more further diffuser rings being static rings (e.g. non-rotatable about the horizontal axis)or dynamic diffuser rings (e.g. rotatable around the horizontal axis).