Tensioned Propulsor Fan Array for Stable Blade Pitch and Low Noise
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Solution Overview
Problem
Conventional propulsor fans emit noise due to changes in blade pitch at higher speeds, leading to increased noise pollution, as they are limited by a single-sided support structure and cannot maintain blade angle consistency.
Innovation Solution
A propulsor fan array with tensioned blades, where the tips and roots of the blades are locked to maintain a consistent pitch during thrust generation and at rest, reducing noise by ensuring the same blade angle is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional propulsor fans increase fan speed to emit sound at less perceivable frequencies, then noise frequency becomes less audible, but blade pitch changes become audible and noise pollution increases
Solution Approach 1:
The patent applies dynamic balancing by tensioning the blade tips to counteract centrifugal forces that cause pitch changes during rotation. This dynamic adjustment maintains consistent blade pitch throughout the rotation cycle, preventing audible pitch modulation noise while allowing the fan to operate at higher speeds where the fundamental frequency is less perceivable.
Solution Approach 2:
The patent changes the physical state of the blades by applying tension to the blade tips, which alters the blade's structural parameters. This tensioning prevents pitch changes during rotation, thereby eliminating the modulation noise that would otherwise occur at higher operating speeds.
2Device complexity
If conventional propulsor fans are supported by single-side structure, then device complexity is reduced, but blade pitch changes occur during rotation causing audible noise
Solution Approach 1:
The patent introduces dynamic tensioning of the blades, where the blades are pre-tensioned to resist pitch changes during rotation. This dynamic approach maintains blade pitch consistency without requiring complex dual-side support structures, thus preserving structural simplicity while eliminating audible pitch modulation noise.
3Ease of manufacture
If conventional propulsor fans use two to five blades supported on single side, then manufacturing is simplified, but blade count is limited and noise control is compromised
Solution Approach 1:
The patent applies dynamic tensioning to the blades, which allows the blades to maintain consistent pitch during rotation regardless of blade count. This enables the use of more blades (beyond the conventional 2-5) without compromising noise control, while the tensioning mechanism itself remains relatively simple to manufacture.
Data Source
AI summary
A propulsor fan array having reduced noise emission is disclosed. The propulsor fan array includes a plurality of propulsor fans that collectively generate thrust. Each of the propulsor fans include a blade fan having a plurality of blades. The plurality of blades are tensioned at tips of the plurality of blade fans such that a pitch of the blades during thrust generation is substantially the same as a pitch of the blades at rest. By tensioning the tips of the blades, an angle of the blades is maintained during operation of the propulsor fan thereby reducing noise that may result from changes in the angle of the blades.