Aeroengine Inlet Splitter Plates for Compressor Noise Attenuation
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Solution Overview
Problem
In larger and more powerful turboprop aircraft, compressor noise from the engine intake becomes a dominant noise source during approach phases, necessitating improved noise attenuation strategies as traditional propeller noise reduction methods are less effective at lower power operations.
Innovation Solution
The implementation of an inlet system with pivotally mounted splitter plates that can transition from a stowed to a deployed position, forming partition walls within the inlet duct to increase noise attenuation, combined with acoustic treatment areas on the splitter plates and duct surfaces to target specific noise frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the inlet duct length/diameter ratio is increased to improve noise attenuation, then compressor noise during approach phases is reduced, but the engine inlet performance and fuel burn are adversely affected
Solution Approach 1:
The inlet duct is segmented into multiple sections with splitter plates creating partition walls that divide the single air passage into multiple passages. This segmentation increases the effective noise attenuation path length without proportionally increasing the overall duct length, thereby reducing compressor noise while maintaining engine inlet performance.
Solution Approach 2:
The invention transitions from a simple linear inlet duct to a multi-dimensional structure with partition walls dividing the flow into multiple passages. This dimensional change allows noise attenuation to occur across multiple parallel paths, effectively increasing the noise reduction capability without linearly increasing the duct length that would harm engine performance.
2Object-affected harmful factors
If acoustic treatment areas are expanded on splitter plates and duct surfaces, then noise propagation attenuation is enhanced, but device complexity and manufacturing cost increase
Solution Approach 1:
The acoustic treatment is segmented and applied selectively on specific surfaces of the splitter plates and duct sections rather than uniformly across the entire inlet system. This targeted segmentation reduces the total amount of acoustic treatment material needed while maintaining effective noise propagation attenuation.
Solution Approach 2:
Acoustic treatment areas are applied locally to specific surfaces where they are most effective for noise attenuation, rather than uniformly across all surfaces. This local quality approach optimizes noise reduction performance while minimizing the complexity and cost associated with extensive acoustic treatment coverage.
3Object-affected harmful factors
If splitter plates are deployed to form partition walls, then noise attenuation increases, but the mechanism complexity and potential reliability issues arise
Solution Approach 1:
The splitter plates are designed to be movable between deployed and stowed positions, allowing the inlet system to dynamically adapt to different operating conditions. This dynamic capability enables noise attenuation when needed while maintaining simplicity and reliability when the noise reduction feature is not required.
Solution Approach 2:
The splitter plates are positioned in a stowed configuration during normal operation to maintain system simplicity and reliability, and are deployed in advance when noise attenuation is required during approach phases, ensuring the noise reduction capability is ready when needed without compromising overall system reliability.
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
Enhances noise propagation attenuation by increasing the length/diameter ratio of the inlet duct and expanding acoustic treatment areas, effectively reducing compressor noise during approach phases without significant power or fuel burn impacts.
Implementation Method 1
acoustic treatment areas on the splitter plates and duct surfaces to target specific noise frequencies
Data Source
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AI summary
An aeroengine is provided with a splitter apparatus (46,48,50,52) disposed in a section (44) of ain inlet duct (24). The splitter apparatus can be actuated from a stowed position to a deployed position to allow splitter(s) to selectively move from out of the inlet flow to a position extending into the inlet duct (24) to divide the inlet flow into multiple passages.