Toroidal Propeller Design for Noise Reduction
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Solution Overview
Problem
Conventional propeller designs for multirotor drones generate high acoustic noise, leading to public annoyance and limiting their acceptance in public spaces, while also lacking in thrust efficiency per unit power.
Innovation Solution
A toroidal propeller design featuring a hub with elongate elements where the tip of one propeller element contacts the trailing element, forming a closed structure that enhances stiffness and reduces acoustic signature, utilizing additive manufacturing for fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional propeller designs are used, then structural simplicity is maintained, but acoustic noise is high and thrust efficiency is low
Solution Approach 1:
The propeller is divided into multiple discrete elements (typically 3-5) that are arranged radially around a common hub. Each element can be independently manufactured and optimized, then assembled to form the complete propeller. This segmentation allows for reduced acoustic noise through optimized element spacing and individual element design while maintaining manufacturing simplicity through modular construction.
Solution Approach 2:
The propeller design transitions from a conventional planar configuration to a three-dimensional toroidal structure where blade tips are curved to contact adjacent blades, forming a closed ring. This dimensional change from 2D to 3D space eliminates tip vortices and reduces acoustic noise while the radial symmetry around a central hub maintains structural simplicity and ease of manufacture.
2Power
If conventional propeller designs are used, then manufacturing simplicity is maintained, but thrust per unit power is low
Solution Approach 1:
The propeller is divided into multiple discrete elements (typically 3-5) that are arranged radially around a common hub. Each element can be independently manufactured and optimized, then assembled to form the complete propeller. This segmentation allows for optimized aerodynamic performance of each element to maximize thrust per unit power while maintaining manufacturing simplicity through modular construction.
Solution Approach 2:
The propeller elements are constructed using composite materials, specifically carbon fiber reinforced polymers, which provide high strength-to-weight ratio and excellent aerodynamic properties. This allows for optimized thrust efficiency while the modular composite structure remains manufacturable using conventional composite fabrication techniques for each element.
3Object-generated harmful factors
If propeller blade tips are extended to form closed structure, then acoustic signature is reduced, but structural complexity increases
Solution Approach 1:
The propeller design transitions from a conventional planar configuration to a three-dimensional toroidal structure where blade tips are curved to contact adjacent blades, forming a closed ring. This dimensional change from 2D to 3D space eliminates tip vortices and reduces acoustic noise while the radial symmetry around a central hub maintains structural simplicity.
Solution Approach 2:
The blade tip regions of adjacent propeller elements are merged together to form a continuous closed toroidal structure. This merging eliminates the gap between blade tips that generates tip vortices and acoustic noise, while the symmetrical merging pattern across multiple elements maintains manufacturing simplicity through repeated geometric motifs.
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 toroidal propeller achieves higher thrust per unit power and significantly reduces acoustic noise, particularly in the 1-5 kHz range most sensitive to human hearing, enabling wider drone acceptance and new use cases with improved structural integrity.
Implementation Method 1
The toroidal propeller includes a hub supporting a plurality of elongate propeller elements... each curved propeller element extending into each trailing propeller element
Implementation Method 2
tip of a leading propeller element curves into contact with a trailing propeller element to form a closed structure... significant reduction in the strength of the trailing tip vortex, a key source of aerodynamic noise
Data Source
AI summary
The propeller includes a hub supporting a plurality of elongate propeller elements in which a tip of a leading propeller element curves into contact with a trailing propeller element to form a closed structure with increased stiffness and reduced acoustic signature.