Aerofoil
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Solution Overview
Problem
Existing rotor blade designs face challenges in reducing high-speed impulsive noises and aerodynamic pitching moments, particularly in the supersonic region, and in optimizing tip edge configurations for improved performance and acoustic benefits.
Innovation Solution
The method involves shaping the tip edge of the rotor blade using a Bezier curve constructed from control points, with specific placement of these points to define the planform configuration, allowing for a swept back configuration and anhedral, which is designed using CAD software to enhance aerodynamic performance and acoustic benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional rotor blade tip designs are used, then manufacturing is simpler, but high-speed impulsive noises and aerodynamic pitching moments are not effectively reduced
Solution Approach 1:
The tip edge is shaped using a Bezier curve with control points positioned on a boundary polygon, creating a curved, swept-back configuration that reduces high-speed impulsive noises and aerodynamic pitching moments in the supersonic region
Solution Approach 2:
The invention specifies precise parameter ranges for control point positions (e.g., P1 at spanwise position 93.5%-95.9%R, P2 at 30%-80% along the second side, P3 at 30%-90% along the third side) to optimize the tip edge geometry for noise reduction while maintaining manufacturability
2Force
If conventional rotor blade tip designs are used, then structural simplicity is maintained, but aerodynamic pitching moments are not reduced
Solution Approach 1:
The curved tip edge configuration defined by the Bezier curve and control points reduces aerodynamic pitching moments caused by spanwise flow in the fore and aft sectors of the rotor rotational disc during forward flight
Solution Approach 2:
The tip region is given a specialized curved geometry different from the main blade body, with specific control points positioned to optimize local aerodynamic characteristics for reducing pitching moments while the rest of the blade maintains its standard structure
3Productivity
If standard tip edge configuration is used, then manufacturing is easier, but hover efficiency and stall characteristics are not optimized
Solution Approach 1:
The Bezier curve control points are positioned within specific parameter ranges (P1 at 93.5%-95.9%R spanwise, P2 at 30%-80% along second side, P3 at 30%-90% along third side) to optimize hover efficiency and delay power rise at stall onset while remaining manufacturable
Solution Approach 2:
The tip edge geometry is pre-defined using mathematical Bezier curves with specified control point positions, allowing for optimized aerodynamic performance to be built into the manufacturing process rather than requiring post-manufacturing adjustments
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
An aerofoil (12a, 12b, 12c, 12d) has a main portion of aerofoil cross section, an inner spanwise root end where the aerofoil is in use secured to a supporting structure, and at an outermost spanwise end outboard of the main portion, beyond a tip station, a tip region, and the tip region including a tip edge, the planform configuration of the tip edge lying on a first Bezier curve constructed from at least four control points P1, P2, P3 and P4, the control points P1, P2, P3 and P4 each lying on the periphery of a polygon which bounds the tip region, Bezier control point P1 being located on a leading edge of the aerofoil at the tip station, which is at a spanwise position between 93.5%R and 95.9%R, where first and second sides of the polygon meet, the first side being at the tip station extending perpendicularly to a blade reference axis, which extends spanwise of the main portion of the aerofoil, and the second side being a tangent to the leading edge of the aerofoil at control point P1, which extends between control point P1 to a position where the second side meets a third side of the boundary polygon at a position outwardly of the tip edge, the third side being parallel to the first side and extending between the position where the third side meets the second side, to where the third side and a fourth side meet, control point P2 being located on the second side at a position between 30% and 80% along the second side from P1, control point P3 being located on the third side at a position between 30% and 90% along the third side from where the second and third sides meet, and control point P4 being located at the outermost tip edge point at a trailing edge of the aerofoil, where R is the effective aerofoil span.