Thick Airfoil Shapes for Rotor Blade Neck Drag Reduction
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Solution Overview
Problem
Rotary wing aircraft experience significant aerodynamic disturbances and drag due to the interaction of air streams with the rotor elements, particularly in the reverse flow region, leading to reduced flying qualities, vibrations, and increased aerodynamic drag.
Innovation Solution
A thick airfoil shape with specific profiles is introduced for the blade neck and cuff, characterized by a relative thickness greater than 20%, optimized to minimize air stream separation and drag, and designed to improve penetration and lift-to-drag ratio across varying air stream conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thick airfoil shapes are used for blade necks and cuffs, then structural strength is provided, but aerodynamic drag increases and wake production occurs
Solution Approach 1:
The patent applies parameter changes by optimizing the airfoil profile geometry with specific coordinates (x1, y1) and (x2, y2) that define the thickness distribution. By carefully selecting these parameters within defined ranges, the airfoil maintains structural strength while minimizing drag and preventing flow separation.
Solution Approach 2:
The patent implements local quality by applying different geometric characteristics to different regions of the airfoil. The leading edge region has specific curvature properties while the trailing edge has different characteristics, allowing each region to optimize its local aerodynamic performance while maintaining overall structural integrity.
2Ease of manufacture
If conventional airfoil profiles are used, then manufacturing simplicity is maintained, but air stream separation occurs in reverse flow region
Solution Approach 1:
The patent uses parameter changes by defining specific coordinate values (x1, y1) and (x2, y2) that control the airfoil's thickness distribution. These parameters are optimized to prevent flow separation in the reverse flow region while maintaining a manufacturable geometry that can be produced using conventional molding or machining processes.
Solution Approach 2:
The patent applies curvature principles by designing the airfoil with specific rounded leading and trailing edges defined by the coordinate parameters. This curvature optimization ensures smooth flow attachment and prevents separation, particularly in the reverse flow region, while maintaining geometric simplicity for manufacturing.
3Productivity
If thin airfoil profiles are used for streamlined portion, then aerodynamic performance is optimized, but structural strength at blade root connection is reduced
Solution Approach 1:
The patent applies segmentation by dividing the blade into distinct zones with different airfoil characteristics. The streamlined portion uses thin profiles for aerodynamic efficiency, while the blade neck and cuff regions use thick profiles with optimized coordinates for structural strength, creating a segmented transition that satisfies both requirements.
Solution Approach 2:
The patent implements local quality by assigning different thickness characteristics to different blade regions. The connection regions (blade neck and cuff) have locally increased thickness defined by specific coordinate parameters to provide structural strength, while the outer streamlined portion maintains thin profiles for aerodynamic performance.
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 reduces aerodynamic drag by 17% to 25%, minimizes wake production, and enhances the aerodynamic performance of rotary wing aircraft, improving flying qualities and reducing vibrations.
Implementation Method 1
the thick airfoil shape being optimized to minimize air stream separations and aerodynamic drag
Data Source
AI summary
A thick airfoil shape that is to form a blade neck for blades, the blade neck connecting a blade root to a streamlined portion of the blade, and/or a blade cuff connecting a blade to the hub of an aircraft rotor. The thick airfoil shape has a leading edge and a trailing edge together with thick airfoil profiles for which the particular positions of points defining the maximum thickness of each airfoil profile make it possible to improve the aerodynamic behavior of the thick airfoil shapes and of the rotor during rotation of the rotor while the aircraft is advancing, for the blade both when it is advancing and when it is retreating. The thick airfoil shape also serves to reduce the vibration as generated by a wake from the rotor on a tail boom or a horizontal and/or vertical stabilizer of the aircraft.