Adjustable Propeller Blade Treatments for UAV Noise Control

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Solution Overview

Problem

The increasing presence of aerial vehicles, such as unmanned aerial vehicles, in residential areas has led to noise pollution concerns due to the sound generated by their propellers, which can disturb residents and disrupt peace.

Innovation Solution

Propeller blades are treated with various modifications, including adjustable and stationary features, such as propeller blade treatments and transducers, to alter and reduce sound generation through destructive interference, absorption, and active sound control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If propeller blades are treated with sound absorption materials and acoustic surface compressibility modifications, then sound generation is reduced, but device complexity increases

Engineering Contradiction:
Improvesound generationVSAvoiddevice complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies different acoustic treatments to specific regions of the propeller blade - the leading edge receives sound absorption materials while the trailing edge receives acoustic surface compressibility modifications. This localized approach allows sound reduction without requiring complete coverage, thereby managing device complexity while effectively addressing noise generation at critical locations.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The propeller blade combines multiple materials with different acoustic properties - sound absorption materials (porous or resonant) combined with acoustic surface compressibility modifications. This composite structure enables simultaneous sound absorption and airflow control, reducing overall sound generation while distributing the complexity across functionally integrated components.

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If active sound control systems with transducers are implemented, then sound control is improved, but device complexity increases

Engineering Contradiction:
Improvesound controlVSAvoiddevice complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent implements active sound control through transducers that can dynamically adjust their operation based on flight conditions. These transducers may be activated or deactivated, or adjusted in intensity, depending on the operational requirements, allowing flexible sound control without requiring permanent complex systems operating at full capacity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The active sound control system incorporates feedback mechanisms where sensors monitor sound levels and flight conditions, and this information feeds back to control the transducers. This feedback loop enables adaptive sound control that responds to actual operating conditions, reducing the need for overly complex pre-programmed systems.

Inventive Principle:
Principle #23Feedback

3Object-generated harmful factors

If propeller blade treatments are added to reduce sound, then noise pollution is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvenoise pollutionVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The propeller blade is divided into distinct treatment zones - leading edge regions for sound absorption and trailing edge regions for acoustic surface compressibility modifications. This segmentation allows each treatment type to be applied using optimized manufacturing processes for that specific function, simplifying overall production compared to a monolithic treatment approach.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs porous or resonant sound absorption materials that can be integrated into the propeller blade structure through established manufacturing techniques. These materials may be applied as coatings or embedded structures that utilize existing manufacturing capabilities, reducing the need for entirely new manufacturing processes while still achieving effective noise reduction.

Inventive Principle:
Principle #31Porous materials

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 modifications effectively control, reduce, and alter the sound generated by aerial vehicles, providing quieter operations and minimizing disturbance to nearby residents.

Implementation Method 1

At least one surface region of the propeller blade has an acoustically effective surface compressibility and/or a sound absorber

Methodology Applied
Scientific EffectSound absorption: Acoustic Absorption

Implementation Method 2

At least one surface region of the propeller blade has an acoustically effective surface compressibility

Methodology Applied
Scientific EffectAcoustic surface compressibility: Acoustics

Implementation Method 3

The modifications effectively control, reduce, and alter the sound generated by aerial vehicles

Methodology Applied
Scientific EffectElectroacoustic transduction:

Data Source

PatentEP3736207B1Propeller blade treatments for sound control
Publication Date: 2026.04.15 AMAZON TECH INC
  • EP3736207B1 patent drawingFigure 1
  • EP3736207B1 patent drawingFigure 2A~2B
  • EP3736207B1 patent drawingFigure 3A~3B

AI summary

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.