Bearingless Rotor Blade Flap Deformation via Flexural Actuation
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Solution Overview
Problem
Rotor blades in rotorcrafts face challenges due to varying aerodynamic conditions, leading to vibrations and increased maintenance needs, particularly with discrete flap bearings that are prone to wear and result in higher drag when deflected.
Innovation Solution
A rotor blade with a shear-flexible main profile body and tension-stiff covering skins, featuring a bearingless and hingeless rear profile deformation region, allows for continuous deformation and reduced drag through flexural motion initiated by actuators, eliminating the need for discrete flap bearings and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If discrete flap bearings are used to enable profile deformation, then the rotor blade can adjust to varying aerodynamic conditions, but the bearings are subject to elevated wear due to high frequency operation and environmental factors
Solution Approach 1:
The patent replaces the mechanical bearing system with a bearingless and hingeless flap design. The flap is integrated into the blade structure and deforms the profile through elastic deformation of the blade skin and internal structure, eliminating mechanical contact and wear-prone bearing components while maintaining the ability to adjust profile geometry for adaptive aerodynamic performance
Solution Approach 2:
The invention utilizes the flexible blade skin and thin-walled structure to enable profile deformation. The blade's elastic properties allow the integrated flap to deform the profile contour without requiring mechanical hinges or bearings, achieving adaptive geometry through structural flexibility rather than mechanical articulation
2Force
If an upward flap deflection is used to generate lift, then the lift is increased, but the drag is increased as compared with a neutral or downwardly deflected profile
Solution Approach 1:
The patent employs dynamic profile deformation where the flap geometry and deflection are continuously adjusted based on real-time aerodynamic conditions. This dynamic adaptation allows the system to optimize the lift-drag ratio by deploying flap deflection only when and where needed, rather than maintaining a fixed upward deflection, thereby reducing energy loss from drag while preserving lift generation capability
Solution Approach 2:
The invention applies profile deformation locally at the rear portion of the blade rather than across the entire blade span. This localized deformation at the trailing edge allows for targeted lift enhancement in specific regions while minimizing the overall drag penalty associated with large-scale upward flap deflections across the whole blade
3Ease of operation
If rolling bearings are used to mount the flap movably, then the flap can be controlled via piezoactuator, but the bearings are subject to elevated wear because of high frequency and environmental factors
Solution Approach 1:
The patent replaces the mechanical bearing system with a bearingless and hingeless flap design. The flap is integrated into the blade structure and deforms the profile through elastic deformation of the blade skin and internal structure, eliminating mechanical contact and wear-prone bearing components while maintaining the ability to adjust profile geometry for adaptive aerodynamic performance
Solution Approach 2:
The integrated bearingless flap structure utilizes the blade's own elastic properties and structural flexibility to enable deformation. The system is self-accommodating, requiring no external bearing maintenance or replacement, as the elastic deformation capability is inherent to the blade's construction rather than dependent on wear-prone mechanical components
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 provides a mechanically simple, aerodynamically favorable profile with reduced drag and simplified deformation kinematics, extending the service life and improving dynamic properties by eliminating wear-prone parts and minimizing drag compared to traditional flap profiles.
Implementation Method 1
Control is applied to the flap via a piezoactuator that is arranged at a spacing in a front (as viewed in the profile depth direction) region of the rotor blade. The piezoactuator generates positioning forces, and transfers them via tension elements to the rotor blade flap.
Implementation Method 2
A flexural motion of the main profile body can be initiated via the actuator, by means of which motion the rear profile deformation region can be deformed by way of a curvature, resulting from the flexural motion of the main profile body, of the upper and lower covering skins to yield a rotor blade flap deflection directed in an opposite direction with respect to the flexural motion.
Data Source
AI summary
An aerodynamic profile includes a main profile body defining a profile depth direction and being shear-flexible in the profile depth direction, a tension-stiff and compression-stiff upper covering skin, a tension-stiff and compression-stiff lower covering skin, wherein the upper and lower covering skins envelope the main profile body, a bearingless and hingeless rear profile deformation region disposed at a rear edge region, and at least one actuator disposed in the main profile body. The at least one actuator is configured to initiate a flexural motion of the main profile body resulting in a curvature of the upper and lower covering skins and to deform the rear profile deformation region and so as to yield a flap deflection directed opposite to a direction of the flexural motion.