Aircraft Air Diffuser Noise Reduction via Segmented Flow Path
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Solution Overview
Problem
Conventional aircraft air diffusers often increase ambient cabin noise, making it difficult to maintain a comfortable and quiet environment while meeting the minimum air flow requirements, which can negatively impact passenger experience.
Innovation Solution
The design of air diffusers with an inlet section, a neck section, and an outlet section, along with an orifice plate and a baffle, configured to direct air flow efficiently and quietly, reducing noise levels by creating a tortuous air flow path and backpressure, thus minimizing the number of diffusers needed while maintaining the required air flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional air diffusers are used to meet minimum air flow requirements, then air flow rate is improved, but ambient cabin noise increases
Solution Approach 1:
The air diffuser is divided into multiple functional sections: inlet section, neck section, outlet section, orifice plate, and baffle. Each section performs a specific function to control airflow and reduce noise. The segmentation allows the diffuser to meet air flow requirements while minimizing noise generation through optimized flow paths and pressure distribution.
Solution Approach 2:
The inlet section, neck section, and outlet section are designed with curved transitions rather than sharp angles. The smooth curved surfaces guide airflow gently through the diffuser, reducing turbulence and noise generation while maintaining the required air flow rate to the cabin.
2Object-affected harmful factors
If more air diffusers are installed to reduce noise per diffuser, then ambient cabin noise is reduced, but aircraft weight and complexity increase
Solution Approach 1:
Multiple functions are merged into a single diffuser design: noise reduction, airflow regulation, and cabin pressurization control. The integrated design includes the orifice plate for backpressure creation and the baffle for flow distribution, allowing one diffuser to replace what would traditionally require multiple separate components.
Solution Approach 2:
The diffuser design changes key parameters including the geometry of inlet/outlet sections, the positioning and sizing of the orifice plate, and the configuration of the baffle. These parameter optimizations enable the diffuser to achieve both low noise operation and adequate airflow, reducing the total number of diffusers needed in the aircraft.
3Productivity
If more air diffusers are installed to ensure adequate air flow coverage, then air flow distribution is improved, but aircraft weight increases
Solution Approach 1:
The curved transitions in the inlet, neck, and outlet sections create smooth airflow patterns that distribute air efficiently throughout the cabin. This optimized flow distribution reduces the need for additional diffusers to ensure adequate coverage, thereby reducing overall aircraft weight.
Solution Approach 2:
The diffuser design optimizes geometric parameters including the angles and dimensions of the inlet/outlet sections, the orifice plate configuration, and baffle positioning. These parameter changes enhance airflow distribution efficiency, allowing fewer diffusers to achieve the required 0.55 Ibs/min per occupant FAA minimum.
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 a quiet aircraft cabin environment with sound levels comparable to or less than ambient noise, even at higher flow rates, while reducing the weight and complexity of the aircraft by minimizing the number of diffusers required, thereby saving fuel and maintenance costs.
Implementation Method 1
an orifice plate, to regulate flow and to create backpressure at the inlet
Implementation Method 2
a baffle, downstream of the orifice plate, to spread flow evenly across the lateral width of the outlet... creating a tortuous air flow path
Data Source
Figure 1
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AI summary
Aircraft, air conditioning systems, and air diffusers (14) that may be used to create a quiet, comfortable environment within an aircraft cabin are disclosed. The systems and apparatuses are configured to flow air at a rate that meets and/or exceeds the FAA minimum requirement of 0.55 lbs/min (about 250 g/min) per occupant. In use, even at higher flow rates, the systems and apparatuses are configured to create a quiet cabin experience, by contributing little to ambient cabin noise. Thus, the systems and apparatuses may be used to provide fresh air at a comfortable rate and a comfortable noise level.