Aircraft Air Diffuser With Porous Flow Conditioning for Noise Reduction
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Solution Overview
Problem
Aircraft environmental control systems face challenges in maintaining a quiet and comfortable cabin environment while balancing weight and complexity, as conventional air diffusers contribute noise and increase weight, complexity, and fuel costs at high flow rates.
Innovation Solution
The integration of a duct, grille, and porous flow conditioner in air diffusers creates backpressure to reduce air velocity and noise, featuring a duct with a duct inlet, outlet, and outlet plenum, a grille with a diffuser exit and inlet, and a porous flow conditioner positioned within the outlet plenum to attenuate noise and manage air flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional air diffusers are used to maintain high air flow rates for cabin pressurization and temperature control, then the environmental control system can meet FAA minimum air flow requirements, but noise levels increase and passenger comfort deteriorates
Solution Approach 1:
The patent employs a porous flow conditioner inserted into the duct outlet plenum. This porous material creates tortuous flow paths that dissipate kinetic energy and reduce noise generation while maintaining the required air flow rate. The porous structure allows air to pass through while creating backpressure that reduces exit velocity and associated noise.
Solution Approach 2:
The flow conditioner acts as an intermediary element between the high-velocity air stream from the duct and the cabin environment. It mediates the transition by creating a buffer zone in the outlet plenum that reduces velocity and noise before air enters the cabin, without significantly impeding the overall air flow rate.
2Object-affected harmful factors
If conventional noise reduction devices are added to the air diffuser system, then noise levels decrease, but device complexity and weight increase
Solution Approach 1:
The patent combines the noise reduction function with the existing air diffuser structure by integrating the porous flow conditioner directly into the duct outlet plenum. This merging of noise control with the airflow management structure avoids adding separate complex noise reduction systems while achieving both objectives simultaneously.
Solution Approach 2:
The porous flow conditioner provides noise attenuation through its inherent material properties rather than requiring complex mechanical noise barriers or active noise control systems. The porous structure naturally dissipates sound energy through viscous effects in the tortuous flow paths, simplifying the overall system design.
3Object-affected harmful factors
If air velocity is reduced at the diffuser exit to minimize noise, then noise levels decrease, but the ability to maintain cabin pressure and temperature control deteriorates
Solution Approach 1:
The patent segments the air flow control into two distinct zones: the duct outlet plenum where velocity is reduced through porous media, and the diffuser exit where air is distributed into the cabin. This segmentation allows velocity reduction for noise control while maintaining adequate flow distribution for pressure and temperature control through the diffuser geometry.
Solution Approach 2:
The porous flow conditioner creates distributed flow paths that reduce velocity through extended flow paths and increased surface area interaction, rather than requiring a large reduction in overall flow rate. This allows noise reduction while maintaining sufficient mass flow for cabin environmental control.
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
This configuration reduces noise levels and maintains a comfortable cabin environment with reduced weight and complexity, achieving sound levels below ambient noise and efficient air flow management, thereby enhancing passenger comfort and reducing operational costs.
Implementation Method 1
The porous flow conditioner is configured to create backpressure in the duct
Implementation Method 2
The porous flow conditioner may be configured to reduce noise generated by air flow through the air diffuser assembly
Data Source
AI summary
Aircraft, environmental control systems, and air diffusers that may be used to create a quiet, comfortable environment within an aircraft cabin are disclosed. The air diffusers include a duct, a grille, and a porous flow conditioner positioned at least partially within an outlet plenum of the duct. The porous flow conditioner is configured to create backpressure and to reduce a velocity of air flowing out of the porous flow conditioner, relative to air flow unaffected by the porous flow conditioner. The porous flow conditioner may be configured to reduce noise generated by air flow through the air diffuser assembly, relative to air flow unaffected by the porous flow conditioner. The porous flow conditioner may be configured to reduce noise generated by air flow downstream of the porous flow conditioner.