Bypass Air Flow Assembly for Low Inlet Pressure Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft air cycle machine (ACM) pack systems face reduced performance at low inlet pressures due to decreased power, leading to inefficiencies in cooling and air flow, particularly at higher altitudes, which complicates meeting cooling and air flow requirements while maintaining necessary cabin conditions.
Innovation Solution
The implementation of a bypass air flow assembly with a parallel turbine or turbo-compressor assembly in the ACM pack system, which transfers energy from bypass air flow to aid the air cycle machine in cooling performance at low inlet pressures, improving efficiency and maintaining air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ACM pack is designed to meet cooling performance at low inlet pressure, then cooling performance is improved, but system size and weight increase
Solution Approach 1:
A turbo-compressor assembly is introduced as an intermediary device between the bleed air system and the ACM pack. This turbo-compressor receives bypass air flow from the bleed air system and transfers energy to the ACM pack inlet, effectively mediating the energy transfer to improve cooling performance without requiring a larger ACM pack
Solution Approach 2:
The system changes the pressure and energy parameters of the air flow by using a turbo-compressor to compress bypass air and transfer energy to the ACM inlet. This parameter change allows the ACM to operate effectively at low inlet pressures by receiving boosted pressure from the turbo-compressor rather than relying on natural bleed air pressure
2Temperature
If air flow is reduced to maintain cold output temperature at low inlet pressure, then cooling temperature is preserved, but air flow requirement compliance deteriorates
Solution Approach 1:
The air flow path is segmented into multiple streams: a primary stream through the ACM pack for cooling, and a bypass stream that is compressed by the turbo-compressor and transferred back to the ACM inlet. This segmentation allows independent control of cooling temperature and total air flow delivery to the cabin
Solution Approach 2:
The turbo-compressor assembly performs multiple functions: it compresses bypass air, transfers energy to the ACM pack, and enables the system to simultaneously meet both temperature and air flow requirements. This multi-functionality resolves the contradiction between maintaining temperature and delivering sufficient air flow
3Device complexity
If the ACM pack operates at reduced power due to low inlet pressure, then system simplicity is maintained, but cooling efficiency deteriorates
Solution Approach 1:
The system converts the harmful effect of low inlet pressure (which reduces ACM power and efficiency) into a benefit by using the turbo-compressor to capture energy from bypass air flow and transfer it to the ACM inlet. The low pressure condition that would normally harm performance is compensated by the energy transfer mechanism
Solution Approach 2:
The solution uses pneumatic energy transfer through the turbo-compressor system, which utilizes the pressure differential and kinetic energy of the bypass air flow to drive the compression process and transfer energy to the ACM pack, improving cooling efficiency without electrical power
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 the ACM pack system's cooling performance and efficiency at low inlet pressures, enabling compliance with Federal Aviation Regulation requirements without increasing system size or weight, thus maintaining effective cabin conditions.
Implementation Method 1
transfers energy extracted from the bypass air flow to the ACM
Implementation Method 2
at least one compressor of the air cycle machine mechanically coupled to at least one turbine in series on an air cycle machine shaft
Implementation Method 3
at least one turbine of the air cycle machine mechanically coupled to at least one compressor in series on an air cycle machine shaft
Implementation Method 4
a pack heat exchanger coupled to and in fluid communication with the at least one compressor of the air cycle machine
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An air cycle machine (ACM) pack system (10) for an aircraft (12) with an improved low inlet pressure cooling performance is provided. The ACM pack system (10) has an air cycle machine (ACM 42) with at least one compressor (72) mechanically coupled to at least one turbine (74) in series on an ACM shaft (78). The ACM pack system (10) further has a pack heat exchanger (44) coupled to and in fluid communication with the at least one compressor (72) of the ACM (42). The ACM system further has a bypass air flow assembly (11) coupled in a parallel operation path to the ACM (42) and has a bypass air flow regulating element (86). The bypass air flow assembly (11) transfers energy extracted by the bypass air flow assembly (11) to the ACM (42) to aid the ACM pack system (10) in cooling performance at a low inlet pressure, resulting in an improved low inlet pressure cooling performance of the ACM pack system (10).