Variable Speed Recirculation Fan for Aircraft Cabin Airflow Control
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Solution Overview
Problem
Aircraft fuel efficiency is reduced due to constant airflow requirements, especially when air conditioning packs use bleed air, and existing systems lack efficient methods to adjust airflow based on passenger occupancy and cabin conditions.
Innovation Solution
A system with a variable speed recirculation fan and external air supply device, controlled by a controller that adjusts airflow rates based on occupancy and operational conditions, including sensors for contaminant detection, to optimize airflow and reduce external air intake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of outside air provided by air conditioning packs increases to maintain cabin air quality, then cabin air quality is improved, but aircraft fuel efficiency is reduced
Solution Approach 1:
The recirculation fan speed is made variable rather than constant, allowing the system to dynamically adjust the recirculation flow rate based on cabin occupancy and air quality conditions. This enables optimization of the balance between outside air intake and recirculated air, improving fuel efficiency while maintaining adequate cabin air quality.
Solution Approach 2:
A controller monitors cabin conditions and adjusts the recirculation fan speed accordingly. The system uses feedback from sensors and occupancy information to modulate the recirculation flow rate, enabling the system to reduce outside air intake when recirculation can maintain adequate air quality, thereby improving fuel efficiency.
2Productivity
If recirculation fans run at constant speed to maintain volumetric airflow, then cabin airflow requirements are met, but fuel efficiency is reduced due to excessive outside air intake
Solution Approach 1:
The recirculation fan operates at variable speeds rather than constant speed, allowing the system to adjust recirculation flow rate dynamically. This enables the maintenance of required volumetric airflow to the cabin while optimizing the mix of outside and recirculated air to improve fuel efficiency.
Solution Approach 2:
The system changes the operational parameters of the recirculation fan (rotation speed) to optimize performance. By adjusting fan speed based on cabin conditions and occupancy, the system maintains adequate airflow while reducing the proportion of outside air required, thereby improving fuel efficiency.
3Loss of energy
If the amount of outside air is reduced to improve fuel efficiency, then fuel economy is improved, but cabin air quality may deteriorate
Solution Approach 1:
The variable speed recirculation fan allows the system to dynamically adjust recirculation flow rate based on cabin air quality conditions and occupancy. This enables the system to reduce outside air intake for fuel efficiency while compensating with increased recirculation to maintain adequate cabin air quality.
Solution Approach 2:
The controller monitors cabin air quality and adjusts recirculation fan speed to compensate for reduced outside air intake. This feedback mechanism ensures that cabin air quality is maintained even when outside air provision is reduced to improve fuel economy.
4Loss of energy
If manual entry of passenger number is required to adjust outside air flow, then airflow can be optimized for occupancy, but system complexity and operational burden increase
Solution Approach 1:
The system automatically determines cabin occupancy using sensors and existing aircraft systems rather than requiring manual input from crew. This self-service approach eliminates the operational burden of manual entry while maintaining optimized outside air flow based on actual occupancy.
Solution Approach 2:
The manual mechanical input system for occupancy entry is replaced with automated sensor-based occupancy detection. This substitution eliminates the need for crew intervention while providing continuous, accurate occupancy data for optimizing outside air flow.
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 solution enhances fuel efficiency by varying airflow rates, maintaining cabin comfort and quality while reducing external air intake, thereby improving aircraft fuel economy and air quality.
Implementation Method 1
a recirculation fan configured to move air positioned within the interior volume between the first portion of the interior volume and the second portion of the interior volume
Implementation Method 2
determining a rotation speed of a variable speed recirculation fan that will provide at least approximately the selected recirculation flow rate and rotating the recirculation fan at least approximately at the rotation speed
Data Source
Figure 1
Figure 2
AI summary
Systems and methods for providing airflow in an aerospace vehicle are disclosed. A system in accordance with one embodiment includes an aerospace vehicle having an interior volume with a first portion and a second portion. The system can further include an external air supply device positioned to provide supply air to the interior volume at a variable supply flow rate and a recirculation fan configured to move air positioned within the interior volume between the first portion of the interior volume and the second portion of the interior volume. The system can still further include a controller operably coupled to the recirculation fan and configured to vary a rotation speed of the recirculation fan. Variations in the rotation speed of the recirculation fan can be associated with variations in a recirculation flow rate. In selected embodiments, the system can include sensors and/or data link devices operably coupled to the controller.