Variable-Height Rotor Blade Protrusions for Rotary-Wing Noise Reduction
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Solution Overview
Problem
Rotary wing aircrafts generate significant noise during operation, limiting their application scenarios and requiring improved noise reduction techniques.
Innovation Solution
The implementation of protruding structures on the blade surface, arranged in a spanwise direction with varying heights and shapes, to induce forced turbulence transition and reduce laminar separation bubbles, enhancing airflow attachment and minimizing noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If protruding structures with varying heights are arranged on the blade surface, then noise reduction effect is improved, but device complexity increases
Solution Approach 1:
The blade surface is equipped with protruding structures at specific locations rather than uniformly across the entire surface. The protruding structures are arranged in sequences along the spanwise direction with varying heights (first, second, and third heights) at different positions, creating local quality variations that trigger turbulence transition precisely where needed to reduce noise without unnecessarily complicating the entire blade structure.
Solution Approach 2:
The noise reduction solution is segmented into multiple discrete protruding structures rather than using a single continuous modification. These protruding structures are arranged in separate sequences (first sequence, second sequence, third sequence) at different spanwise positions, allowing independent optimization of each segment's height and positioning to achieve cumulative noise reduction效果 while managing overall structural complexity.
2Productivity
If protruding structures are added to the blade surface, then aerodynamic efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies parameter ranges for the protruding structures rather than fixed values, providing manufacturing flexibility. The height parameters are defined as ranges (first height range, second height range, third height range) rather than exact values, and the spanwise positioning is defined by distance ranges from the blade root. This parametric approach allows manufacturing within tolerances while maintaining the aerodynamic effectiveness of triggering turbulence transition.
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 design effectively reduces noise levels by up to 5 dBA, improving aerodynamic efficiency while maintaining aircraft performance.
Implementation Method 1
a contact region with air is increased by means of the plurality of protruding structures having the height difference to achieve forced turbulence transition on a laminar separation bubble of the blade
Implementation Method 2
a thickness of a boundary layer of a trailing edge is reduced
Data Source
Figure 1~3
Figure 4
AI summary
The present application discloses a rotor. The rotor comprises a blade, a plurality of protruding structures protrude from the surface of the blade, the plurality of protruding structures are sequentially arranged at intervals in the spanwise direction of the blade, and a height difference is formed between every two adjacent protruding structures.