Cabin Pressure Control System Architecture for APU Compressor Inlet
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Solution Overview
Problem
Current cabin pressure control systems (CPCSs) face challenges in efficiently providing pressurized air to aircraft APU core compressors while maintaining safe and comfortable cabin pressure, especially during flight and ground operations, and in handling failure conditions such as APU shut-off or decompression.
Innovation Solution
A pressure control system comprising an outflow valve, positive and negative pressure relief valves, and a control valve, along with a controller, that regulates air flow between the cabin and APU compressor, ensuring efficient air distribution and redundancy to manage pressure and ventilation needs, including the use of redundant channels and sensors for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cabin air exhaust is used to provide aft thrust via thrust recovery valve, then thrust is generated, but the valve becomes very large, heavy, and expensive with high aerodynamic torques requiring large rotary actuators
Solution Approach 1:
The invention extracts the thrust recovery function from the traditional thrust recovery valve and relocates it to the APU core compressor inlet. By taking out the exhaust air flow path and directing it to the APU compressor, the system eliminates the need for large thrust recovery valves and their associated heavy actuators while still generating useful thrust.
Solution Approach 2:
The APU core compressor is given multiple functions: it serves both as the air source for APU operation and as a thrust generation device. The same component that compresses air for APU operation also utilizes the exhaust air flow to generate aft thrust, eliminating the need for separate dedicated thrust recovery hardware.
2Productivity
If cabin air exhaust is consumed by APU core compressor to increase operating efficiency, then APU efficiency increases, but the system must manage cabin pressure control and failure conditions
Solution Approach 1:
The system segments the air flow control into separate independent pathways: a primary pathway for cabin pressure control through the outflow valve, and a secondary pathway for APU air supply through the control valve. This segmentation allows the APU to draw exhaust air for efficient operation while the outflow valve independently manages cabin pressure, ensuring safety even if one system fails.
Solution Approach 2:
The system incorporates redundant control valves and sensors that stand ready to activate if the primary APU shut-off valve fails or becomes stuck. This beforehand cushioning ensures that if the normal air flow path is blocked, the redundant components can immediately take over to maintain proper cabin pressure and prevent decompression.
3Adaptability or versatility
If thrust recovery valve is made large to handle ground operations with low pressure ratio, then thrust is generated, but the valve and actuator become very heavy and expensive
Solution Approach 1:
The invention extracts the ground operation thrust recovery function from the traditional valve design and integrates it into the APU core compressor system. By taking out the exhaust air flow and directing it to the APU compressor inlet, the system generates thrust without requiring large, heavy valves capable of handling low pressure ratio ground operations.
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 system effectively provides pressurized air to the APU compressor, maintains safe cabin pressure, and ensures proper ventilation, even in failure conditions, by modulating air flow and using redundant components to prevent decompression and maintain structural pressure limits.
Implementation Method 1
an outflow valve configured to regulate a discharge of air from the first environment
Implementation Method 2
a positive pressure relief valve configured to regulate a discharge of air from the first environment
Implementation Method 3
a negative pressure relief valve configured to regulate an ingress of air into the first environment
Implementation Method 4
a control valve configured to supply and regulate pressurized air from the first environment to a compressor
Implementation Method 5
compressor core compressors
Data Source
AI summary
A pressure control system includes an overboard valve in indirect communication with a first enclosed environment and in direct communication with a second enclosed environment. The first environment is suitable for human occupancy and configured to receive pressurized air from an environmental control system. The second environment is configured to receive the pressurized air from the first environment. An inboard valve is configured to supply a discharge of pressurized air from the second environment. An outflow valve is configured to regulate a discharge of air from the first environment to an area outside the first and second environments. A positive pressure relief valve configured to regulate a discharge of air from the first environment. A negative pressure relief valve configured to regulate an ingress of air into the first environment. A control valve is configured to regulator and supply pressurized air from the first environment to a compressor.