Helicopter Engine Acoustic Attenuator Inlet Lips
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Solution Overview
Problem
Existing gas turbine engine helicopters face significant noise emissions due to the motor driving the main rotor blades, and current sound reduction methods, such as acoustic attenuators, often require design modifications and increase the engine's bulk and mass.
Innovation Solution
A soundproofing device for gas turbine helicopter engines featuring air inlet lips with integrated acoustic attenuators that attenuate sound frequencies produced by the compressor, which are located externally on the metal casing, allowing for effective noise reduction without altering the engine design or increasing mass, and can be applied to existing engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If acoustic attenuators are integrated into the engine design, then noise emission is reduced, but the engine bulk and mass increase
Solution Approach 1:
The acoustic attenuator is extracted from the internal engine structure and relocated to the external air inlet lips. This allows the noise reduction function to be separated from the engine core, avoiding the need to increase engine bulk and mass while still achieving effective noise attenuation at the source
Solution Approach 2:
The acoustic attenuator is applied locally at the air inlet lips where noise enters the engine system, rather than throughout the entire engine structure. This localized application reduces noise effectively while minimizing the addition of mass and bulk to the overall engine
2Object-generated harmful factors
If acoustic attenuators are integrated into the engine design, then noise emission is reduced, but the engine design must be modified
Solution Approach 1:
The acoustic attenuator function is extracted as a separate, modular component that attaches to the external air inlet lips. This modular approach allows noise reduction to be added without modifying the core engine design, maintaining simplicity while achieving the noise reduction goal
Solution Approach 2:
The noise reduction system is segmented into a separate, independent component (the acoustic attenuator at the air inlet lips) rather than being integrated into the engine structure. This segmentation allows the attenuator to be added or removed without affecting the engine design, reducing overall system complexity
3Object-generated harmful factors
If acoustic attenuators are added to reduce noise, then noise emission is reduced, but space requirements increase
Solution Approach 1:
The acoustic attenuator is placed on the external air inlet lips, utilizing space outside the engine volume. This extraction from the internal engine structure allows noise reduction without increasing the engine's internal volume or displacing other engine components
Solution Approach 2:
The acoustic attenuator utilizes the external dimensional space around the air inlet lips rather than consuming internal engine volume. By moving the noise reduction function to an external location, the engine's internal volume requirements remain unchanged while still achieving effective noise attenuation
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 solution provides efficient noise attenuation, optimizing aerodynamic design without space or mass concerns, and maintains the possibility of anti-icing grid coverage, making it suitable for existing engines.
Implementation Method 1
at least partly formed by an acoustic attenuator capable of attenuating the sound frequencies produced by the rotation of the compressor
Data Source
Figure 1
Figure 2~3
AI summary
The device has a compressor e.g. centrifugal compressor, and an annular passage (12) for supplying air to the compressor. A radial air inlet (34) including lips (30, 32) is connected to the passage in which the lips are partially formed by acoustic attenuators (40, 42) e.g. Helmholtz attenuators. The attenuators attenuate sound frequencies produced by rotation of the compressor, where the lips are made of fibrous reinforcement composite material densified by resin. Another set of acoustic attenuators is integrated to a metallic case (14) defining the passage of the compressor.