Supersonic Aircraft Shield and Exhaust Nozzle for Noise Reduction
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Solution Overview
Problem
Current technologies fail to effectively reduce both sonic booms and jet noise during take-off and landing of supersonic aircraft, as existing noise-reducing methods either focus on one aspect or result in trade-offs between noise reduction and sonic boom mitigation.
Innovation Solution
A supersonic aircraft design incorporating a shield to reduce sonic booms and a specific exhaust nozzle that generates high-frequency sound sources at positions where the shield can shield them, promoting mixing with external airflow to reduce low-frequency noise components, thereby addressing both sonic booms and jet noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-noise nozzles with modified exit shapes are used to reduce jet noise, then low-frequency noise components are reduced, but high-frequency noise components increase
Solution Approach 1:
The patent applies local quality by creating different flow conditions at different locations within the exhaust jet. The nozzle exit shape modification (such as Chevron or serrated edges) locally disturbs the flow to promote mixing in specific regions, which reduces low-frequency noise from the jet plume while the shield strategically blocks high-frequency noise sources near the engine exit.
Solution Approach 2:
The patent introduces a shield as an intermediary component between the engine exhaust and the external environment. This shield acts as a mediator that selectively blocks high-frequency noise components while allowing the modified nozzle to effectively reduce low-frequency noise, thereby resolving the trade-off between reducing one frequency band while potentially increasing another.
2Object-affected harmful factors
If shields are added to reduce sonic booms, then sonic boom noise is reduced, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the shield to serve multiple functions simultaneously. The same shield structure that reduces sonic boom noise also helps block high-frequency jet noise components, particularly in the lateral directions. This multi-functionality reduces the need for separate components and minimizes overall device complexity while achieving multiple noise reduction goals.
3Object-affected harmful factors
If jet noise is reduced by modifying exhaust flow, then airport noise during take-off and landing is reduced, but the effectiveness varies by propagation direction
Solution Approach 1:
The patent applies local quality by creating direction-specific noise reduction characteristics. The shield is positioned and shaped to provide targeted shielding in specific propagation directions (particularly lateral directions at polar angles of 90-150 degrees), while the nozzle modification addresses downstream propagation. This allows optimized noise reduction for different airport noise sensitivity zones.
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 achieves significant noise reduction, particularly at polar angles of 110 to 140 degrees, exceeding the combined effects of using the shield or nozzle alone, effectively addressing the challenges of sonic booms and airport noise.
Implementation Method 1
shock waves generated from the respective parts of the airframe integrate as they propagate long distances in the atmosphere
Implementation Method 2
promotes mixing of the engine exhaust flow that generates low-frequency noise components with an external air flow to thereby reduce jet noise having the low-frequency components
Implementation Method 3
generates a sound source for high-frequency components at a position at which the shield is capable of shielding the high-frequency components
Data Source
AI summary
Provided is a supersonic aircraft including: a shield that shields an engine exhaust flow discharged from a jet engine accommodated in an engine nacelle mounted on a fuselage of the aircraft to thereby reduce sonic booms due to the engine exhaust flow; and an exhaust nozzle that is provided in an exhaust port of the engine nacelle and that generates a sound source for high-frequency components at a position at which the shield is capable of shielding the high-frequency components of the engine exhaust flow, to thereby reduce jet noise having the high-frequency components, and promotes mixing of the engine exhaust flow that generates low-frequency noise components with an external air flow to thereby reduce jet noise having the low-frequency components.