Multi-Ring Diffuser Augmented Wind Turbine Drag Reduction
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Solution Overview
Problem
Conventional diffuser-augmented wind turbines require large, bulky cowlings to achieve significant air acceleration, leading to increased drag, structural load, and economic costs, while also being aesthetically undesirable due to their size and visibility.
Innovation Solution
A diffuser design with static, non-rotatable rings having an expanded outlet area greater than the inlet area, combined with vent structures and suction slots, and constructed from aero-elastic materials to reduce drag and structural complexity, allowing for efficient airflow acceleration without the need for large expansions in cross-sectional area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional diffusers use large expansion in exit area to increase wind speed, then power output and efficiency are improved, but drag and structural load increase significantly
Solution Approach 1:
The patent transitions from a conventional single-plane diffuser to a multi-ring three-dimensional diffuser structure. The diffuser comprises a first ring with inlet and outlet areas, and one or more second rings downstream with progressively smaller inlet areas. This multi-dimensional arrangement creates multiple airflow paths and pressure gradients, accelerating wind through the rotor plane without requiring a single large expansion, thereby reducing drag while maintaining power output.
Solution Approach 2:
The diffuser is segmented into multiple independent rings (first ring and one or more second rings) rather than a single monolithic structure. Each ring functions as a separate flow control element with its own inlet and outlet areas. This segmentation allows the system to achieve cumulative acceleration effects through multiple stages while reducing the drag burden on any single structural component.
2Speed
If conventional diffusers expand exit area to accelerate airflow, then wind speed increases, but the size and visibility of the turbine increase
Solution Approach 1:
The patent employs a multi-ring three-dimensional configuration where the diffuser extends along the airflow direction with progressively smaller rings downstream. This arrangement achieves wind acceleration through cumulative pressure gradients across multiple rings rather than requiring a single large cross-sectional expansion, thereby reducing the overall visible footprint and size of the diffuser structure.
Solution Approach 2:
The diffuser rings are arranged in a nested configuration where second rings are positioned downstream and partially within the flow path of the first ring. The inlet area of second rings is smaller than the outlet area of the first ring, creating a telescoping effect that achieves significant acceleration while minimizing the external dimensions and visual profile of the entire diffuser assembly.
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 solution enhances wind energy conversion efficiency beyond theoretical limits, reduces drag and structural loads, and minimizes visual impact by achieving significant air acceleration with a compact diffuser design, thereby improving power output and reducing operational costs.
Implementation Method 1
the diffuser has an expanded outlet area... to accelerate airflow to the rotor plane
Implementation Method 2
Diffuser augmented wind turbines... diffuser or ducting arrangements that accelerate airflow
Implementation Method 3
constructed from aero-elastic materials to reduce drag and structural complexity
Data Source
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AI summary
Diffuser augmented wind turbines are described below. In an embodiment a wind turbine diffuser has an expanded outlet area where the diffuser outlet area is greater than it's cross sectional area. In an example,the diffuser may be formed of one or more diffuser rings, at least one of which may form a turbine cowling. Each diffuser ring may have an inlet area that is smaller than the outlet area of the directly upstream ring. In an example the portion of an upstream ring outlet which is not occluded by the downstream ring may form a diffuser outlet such that the total outlet area of the diffuser is larger than the cross-sectional area. In another example,the diffuser may comprise at least one diffuser ring and one or more suction slots that are each connected to a vent,which allows air to be removed from the diffuser system.