Aircraft Engine Nacelle Fluid Sheet Jets for Noise Reduction
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Solution Overview
Problem
Aircraft engines generate significant noise during takeoff phases due to the high-velocity ejection of gas streams, which causes interactions with surrounding air and results in considerable noise pollution.
Innovation Solution
The implementation of a system with multiple conduits distributed around the downstream end of the engine nacelle, each ejecting a fluid jet in the form of a sheet, creating a fluid curtain that reduces the interaction between the gas streams and surrounding air, thereby minimizing noise. This system can be integrated into the engine's design, either externally or internally, and may include chevrons to enhance noise attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas stream is ejected at high velocity to maintain thrust and power, then the engine productivity is improved, but the noise generated by the encounter between the ejected gas stream and surrounding air increases significantly
Solution Approach 1:
The patent introduces an intermediary substance (fluid from the secondary stream) that is injected between the primary gas stream and the surrounding air. This intermediary fluid acts as a buffer or curtain that reduces the direct interaction and turbulent mixing between the high-velocity gas stream and ambient air, thereby reducing noise generation while preserving the thrust-producing capability of the primary stream.
Solution Approach 2:
The invention utilizes pneumatic principles by injecting a fluid stream (secondary stream) to control and modify the flow characteristics around the primary gas stream. The injected fluid creates a protective boundary layer that suppresses turbulent mixing and noise, leveraging fluid dynamics to solve the noise problem without compromising the aerodynamic performance and thrust of the engine.
2Power
If the gas stream interacts with surrounding air to achieve mixing and thrust, then the engine performance is improved, but the noise generated by the interaction increases
Solution Approach 1:
The secondary stream acts as an intermediary that facilitates controlled mixing between the primary gas stream and surrounding air while reducing noise. By injecting this intermediate fluid, the patent creates a gradual transition zone that allows for effective mixing and thrust generation without the violent turbulent interactions that produce noise.
Solution Approach 2:
The invention changes the flow parameters by introducing a secondary fluid stream that modifies the velocity profile, pressure distribution, and turbulence characteristics of the primary gas stream. This parameter modification creates a more favorable flow environment that maintains engine performance while suppressing noise-generating turbulent mixing.
3Productivity
If a single large jet is used to eject the gas stream, then the thrust is maximized, but the noise is increased due to stronger interaction with surrounding air
Solution Approach 1:
The patent segments the gas stream ejection into multiple smaller jets distributed around the periphery of the engine outlet. Instead of a single large jet, the primary stream is divided into several smaller streams that are spaced apart, allowing the secondary stream to be injected between them. This segmentation reduces the interaction between each individual jet and the surrounding air, thereby reducing noise while maintaining total thrust.
Solution Approach 2:
The invention adds a radial dimension to the jet arrangement by positioning multiple jets around the periphery of the engine outlet in a circular pattern. This three-dimensional distribution of jets allows for better integration with the secondary stream injection, creating a multi-dimensional flow control system that reduces noise while preserving thrust effectiveness.
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 fluid curtain effectively reduces noise generation by modifying turbulence patterns and preventing the entrainment of external air into the high-speed gas stream, resulting in a significant decrease in noise levels during takeoff and approach phases without compromising aerodynamic performance or thrust.
Implementation Method 1
a plurality of conduits distributed over the periphery of the downstream end of the wall are each capable of ejecting, via an outlet orifice, a fluid jet in the form of a sheet
Implementation Method 2
the encounters between the ejected air and the surrounding air and between the primary stream and the secondary stream generate considerable noise
Implementation Method 3
the external stream is less easily entrained by the high-speed ejection of the gas stream than heretofore
Implementation Method 4
These vortices profoundly modify the nature of the turbulence and the modes of interaction between the ejected fluid and the ejected gas stream
Data Source
AI summary
An aircraft engine having a longitudinal axis, including a wall surrounding a gas stream that is ejected at a downstream end of the wall along the longitudinal axis, wherein a plurality of conduits distributed at the periphery of the downstream end of the wall are each capable of ejecting, via an outlet orifice, a fluid jet in the form of a sheet, in such a way that the jets thus ejected each form a fluid perturbation around the ejected gas stream.