Flexible Rotor Blade Tip Extension for Tight Duct Clearance
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Solution Overview
Problem
Ducted rotor systems face challenges in maintaining a constant tight clearance distance between rotor blades and the rotor duct due to manufacturing and operational tolerances, aerodynamic loads, and forces, which affects their efficiency and performance.
Innovation Solution
The implementation of flexible tip extensions made from materials like elastomers or flexible materials with outboard ends featuring flexible elements, such as linear or curved cuts, or bristles, which are affixed to the rotor blades to extend their length and maintain a minimized clearance distance while accommodating unintended contacts with the rotor duct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rigid tip extensions are used to minimize clearance distance, then aerodynamic efficiency is improved, but the system becomes sensitive to manufacturing tolerances and operational variations
Solution Approach 1:
The tip extension transitions from a rigid structure to a flexible structure by changing the material parameter (using elastomers or flexible materials with outboard ends featuring flexible elements). This parameter change allows the tip extension to adapt its shape and clearance distance dynamically, resolving the contradiction between maintaining tight clearance for aerodynamic efficiency and accommodating manufacturing tolerances.
Solution Approach 2:
The tip extension is designed with flexible elements that allow it to dynamically adjust its position and shape in response to operational conditions. This dynamic capability enables the system to maintain optimal clearance distances despite manufacturing variations and operational loads, eliminating the need for extremely tight manufacturing tolerances while preserving aerodynamic efficiency.
2Productivity
If tight clearance distance is maintained to improve ducted rotor effectiveness, then performance is enhanced, but unintended contacts cause damage and reduce reliability
Solution Approach 1:
The tip extension material changes from rigid to flexible (using elastomers or flexible materials), which fundamentally alters the interaction dynamics during unintended contact. The flexible material absorbs impact energy through deformation rather than transmitting it to the rotor duct, resolving the contradiction between maintaining tight clearance for effectiveness and protecting against damage during unintended contact.
Solution Approach 2:
The flexible elements in the tip extension act as a pre-designed cushioning mechanism that absorbs impact energy during unintended contacts with the rotor duct. This beforehand cushioning protects both the tip extension and the rotor duct from damage, allowing the system to operate with tight clearances for enhanced effectiveness without compromising reliability.
3Strength
If rigid rotor blade tips are used, then structural strength is maintained, but replacement of worn parts is difficult and complex
Solution Approach 1:
The rotor blade is segmented into a rigid inboard portion and a flexible outboard tip extension. This segmentation allows the tip extension to be designed as a separate, replaceable component that can be easily removed and replaced without affecting the main blade structure. The rigid portion maintains overall blade strength while the separable flexible tip enables easy replacement, resolving the contradiction between structural strength and ease of repair.
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 solution allows for reduced manufacturing and assembly tolerances, easier replacement of worn parts, and absorption of contact energies, thereby enhancing the ducted rotor system's effectiveness and reducing damage during unintended contacts.
Implementation Method 1
The flexible elements may be configured to contact the rotor duct and absorb contact energies
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A rotor system (280) is provided in one example embodiment and may include a rotor duct (220); at least one rotor blade (200), wherein the at least one rotor blade (200) comprises a tip end (204); and a tip extension (230) affixed at the tip end (204) of the at least one rotor blade (200), wherein the tip extension (230) is comprised, at least in part, of a flexible material and the rotor blade (200) has a fixed extended length (212b) based on the tip extension (230). The tip extension (230) may provide a clearance distance (216) between the tip extension (230) and the rotor duct (220).