Aircraft Air Intake Structure for Whistling Noise Suppression
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Solution Overview
Problem
Existing aircraft air intake devices generate significant aerodynamic noise due to the coupling of return airflow and disturbed flow in closed cavities, leading to whistling sounds.
Innovation Solution
Incorporation of a protrusion positioned upstream of the air inlet, a skirt surrounding the air inlet, and a deflector to minimize airflow disturbances and reduce noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed cavity is formed by the air inlet and intake duct when the valve is closed, then the air intake device can effectively seal and control airflow, but aerodynamic noise including whistling sounds is generated due to coupling between return airflow and disturbed flow
Solution Approach 1:
A protrusion is introduced as an intermediary element within the closed cavity to modify the airflow pattern. This protrusion acts as a mediator that disrupts the coupling between return airflow and disturbed flow, thereby reducing aerodynamic noise while preserving the sealing function of the closed cavity configuration.
Solution Approach 2:
The protrusion creates local variations in the cavity structure, changing the flow characteristics in specific regions. By modifying the local geometry at strategic positions within the cavity, the overall aerodynamic noise is reduced without compromising the global sealing performance of the air intake device.
2Loss of energy
If the air inlet is positioned flush with the aerodynamic wall, then aerodynamic drag is reduced, but the structure becomes more sensitive to airflow disturbances that can generate noise
Solution Approach 1:
The protrusion is positioned upstream within the closed cavity to preemptively modify the airflow before it can develop into significant disturbances. By acting in advance on the airflow pattern, the protrusion prevents the formation of noisy flow structures while maintaining the flush-mounted air inlet configuration that minimizes drag.
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 protrusion, skirt, and deflector configuration effectively limit aerodynamic noise by preventing airflow coupling and disturbances, thereby reducing noise generation during flight.
Implementation Method 1
an airflow 24 when the aircraft 10 is in flight
Implementation Method 2
generates aerodynamic noise, including a whistling sound, due to the coupling between a return airflow 24.1 formed in the closed cavity 44 and a disturbed flow 24.2 appearing after the upstream edge 44.1 of the closed cavity 44
Data Source
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AI summary
The invention relates to an aircraft comprising at least one air intake device (46) having an air inlet (48) opening at the level of an aerodynamic wall (50) and having a first end (48.1) positioned on a reference surface (Sr) of the aerodynamic wall (50) substantially parallel to an airflow (56) flowing along the aerodynamic wall (50) during operation. According to the invention, the air intake device (46) includes at least one projection (70) projecting from the reference surface (Sr) and positioned upstream of the air inlet (48) along the direction of airflow (56), near or at the same level as the first end (48.1) of the air inlet (48). This projection helps to limit the generation of aerodynamic noise.