Integrated Secondary Power Unit Control for Aircraft Engine Modes
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Solution Overview
Problem
Existing aircraft propulsion systems have separate installations for auxiliary power units and air cycle machines, leading to inefficiencies and limited integration for power and thermal management.
Innovation Solution
An integrated engine and secondary power unit system with a controller that dynamically selects input energy sources and output types based on operating modes, utilizing bleed taps, compressors, turbines, and an electric motor-generator to optimize power and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary power unit and air cycle machine are installed in physically separate regions, then system reliability is improved through redundancy, but device complexity increases and space utilization deteriorates
Solution Approach 1:
The patent combines the auxiliary power unit and air cycle machine into a single integrated assembly where the APU compressor, turbine, and combustor share common structures with the air cycle machine components. This merging reduces device complexity and improves space utilization while maintaining reliability through the redundant gas turbine-based architecture.
Solution Approach 2:
The integrated assembly enables the same gas turbine components to serve multiple functions: the APU compressor and turbine provide both auxiliary power generation and air cycle machine operation for cabin conditioning. This multi-functionality reduces the number of separate components needed while maintaining system reliability.
2Ease of manufacture
If separate installations are used for auxiliary power unit and air cycle machine, then ease of manufacture is improved through standardized components, but productivity deteriorates due to increased installation time and space requirements
Solution Approach 1:
By merging the APU and air cycle machine into a single integrated assembly with shared components (compressor, turbine, combustor, heat exchangers), the patent reduces installation time and space requirements, thereby improving productivity during aircraft assembly and operation while maintaining ease of manufacture through standardized gas turbine components.
3Power
If APU combusts fuel directly while air cycle machine does not, then power output is improved for starting engines, but energy efficiency deteriorates during cabin conditioning operations
Solution Approach 1:
The integrated assembly dynamically switches between different operating modes: using fuel combustion in the APU combustor when high power is needed for engine starting, and switching to electric motor-driven compression when only cabin conditioning is required. This dynamic operation optimizes energy efficiency by avoiding unnecessary fuel combustion during lower-power operations.
Solution Approach 2:
The system changes operational parameters by switching between gas turbine-driven compression and electric motor-driven compression based on power requirements. During cabin conditioning, the system can operate the air cycle machine using electric power from the APU generator rather than direct fuel combustion, improving energy efficiency while maintaining the ability to produce high power when needed.
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
Enhances efficiency and performance by allowing seamless transitions between operating modes, optimizing power and thermal management, and enabling combined power and thermal management systems with improved efficiency and performance characteristics.
Implementation Method 1
A propulsion system for an aircraft can include one or more gas turbine engines that combust fuel and provide propulsive power
Implementation Method 2
The secondary power unit may include a turbine that receives one or more of waste heat from the gas turbine engine, fuel, and pressurized air from the gas turbine engine compressor
Implementation Method 3
The secondary power unit may include an electric motor-generator that may be in a motor mode to drive the compressor or a generator mode to provide electric power
Data Source
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AI summary
An engine system (100, 200) includes a gas turbine engine (120) with a first compressor (124), a first combustor (126), and a first turbine (128). The engine system also includes a secondary power unit (150, 250) with a second compressor (154), a second combustor (156), a second turbine (158), a third compressor (160) coupled to the second compressor, and an electric motor-generator (152), where the secondary power unit is coupled to the gas turbine engine. A controller (180) is operable to determine an operating mode of the engine system, select an input energy source and an output type of the secondary power unit based on the operating mode, control the secondary power unit based on the input energy source and the output type as selected, detect a change in the operating mode of the engine system, and modify the input energy source and/or the output type of the secondary power unit based on the change in the operating mode.