Curved Airfoil Geometry for Attached Flow Around Trailers
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Solution Overview
Problem
Existing airfoils face challenges in efficiently directing airflow around vehicles, particularly trailers, to reduce drag and improve aerodynamics, as they often rely on conventional shapes that do not effectively manage airflow changes and turbulence at edges.
Innovation Solution
The design incorporates airfoils with specific curved portions and geometries, such as elliptic and overhang portions, that utilize the Coandă effect to keep airflow attached and redirect it through large angles, reducing drag by creating a stabilizing force and preventing boundary layer delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional airfoil shapes are used, then manufacturing is simpler, but airflow direction control and drag reduction are insufficient
Solution Approach 1:
The airfoil incorporates an overhang portion with curved surfaces that extend over the base portion, creating a three-dimensional curved structure. This curvature enables the airfoil to effectively redirect airflow by large angles while maintaining attached flow through the Coandă effect, significantly improving aerodynamic efficiency compared to conventional flat or simple curved airfoils.
Solution Approach 2:
The airfoil design transitions from a traditional two-dimensional cross-section to a three-dimensional structure with an overhang portion that extends in the spanwise direction. This dimensional change allows the airfoil to manipulate airflow in multiple directions and create more complex flow patterns that enhance drag reduction and aerodynamic performance.
2Productivity
If airflow is redirected through large angles, then drag reduction improves, but boundary layer delamination occurs
Solution Approach 1:
The airfoil design changes the geometric parameters of the flow path by incorporating an overhang portion with specific curvature and extension distance. This geometric modification alters the flow parameters, enabling the boundary layer to remain attached while turning through large angles. The curved overhang surface provides a gradual pressure gradient that prevents flow separation.
Solution Approach 2:
The overhang portion acts as an intermediary structure between the incoming airflow and the region requiring flow redirection. By providing a curved intermediate surface, the airfoil gradually guides the boundary layer through the turn, preventing direct impingement and separation that would occur with sharp corners or abrupt direction changes.
3Productivity
If turbulent eddies are stabilized, then aerodynamic performance improves, but flow separation increases
Solution Approach 1:
The airfoil design converts the potentially harmful turbulent eddies into a beneficial stabilizing force. The overhang portion is positioned and shaped to allow turbulent eddies to form in a controlled manner, where they create a stabilizing effect on the boundary layer. This stabilization prevents flow separation and maintains attached flow, turning what is typically a harmful phenomenon into a performance-enhancing mechanism.
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
This design effectively turns airflow direction by up to 90 degrees, reducing drag and improving aerodynamics around vehicles by maintaining airflow attachment and stabilizing turbulent eddies, thus enhancing fuel efficiency and reducing void formation behind moving trailers.
Implementation Method 1
The design incorporates airfoils with specific curved portions and geometries, such as elliptic and overhang portions, that utilize the Coandă effect to keep airflow attached and redirect it through large angles, reducing drag by creating a stabilizing force
Data Source
AI summary
Various embodiments of an airfoil and machines with airfoils are disclosed. The airfoils include a thicker leading airfoil portion and a thinner trailing airfoil portion. In one embodiment, the leading airfoil portion is formed by bending a body of the airfoil back toward itself. In another embodiment, the leading airfoil portion has a solid geometry and includes two elliptic surfaces. To prevent detachment of airflow, the leading airfoil portion includes at least two arc portions or surfaces that act to direct the airflow down to the trailing airfoil portion in a manner that stabilizes vortexes that may form in the region of changing thickness.