Integrated Permanent Magnet Alternator and Cooling Fan for Gas Turbine Engine
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Solution Overview
Problem
Gas turbine engines face challenges with large and heavy accessory gearboxes due to multiple accessories and bulky air-to-oil heat exchangers, which occupy space and reduce thrust output.
Innovation Solution
A compact integrated system that includes a permanent magnet alternator and a cooling fan attached to the same shaft, driven by the high-pressure spool, which generates electricity and directs airflow through a heat exchanger to cool lubricating liquids, reducing the size and weight of the gearbox and heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple accessories are added to the accessory gearbox, then the functionality and power supply capability are improved, but the size and weight of the gearbox become undesirably large and heavy
Solution Approach 1:
The patent combines the alternator and cooling fan into a single integrated unit that shares a common shaft and housing. This merging of functions allows the system to provide both electrical power and cooling capabilities while reducing the overall weight and size compared to having separate accessories in the gearbox.
Solution Approach 2:
The integrated alternator-cooling fan assembly serves multiple functions simultaneously: generating electrical power for the engine controller and providing cooling airflow to the heat exchanger. This multi-functionality eliminates the need for separate dedicated cooling equipment, reducing gearbox complexity and weight.
2Temperature
If a relatively large air-to-oil heat exchanger is used to achieve desired cooling, then the cooling effectiveness is improved, but the weight and size of the aircraft increase
Solution Approach 1:
The cooling fan is driven by the alternator shaft, allowing it to operate automatically whenever the alternator is running. This self-service arrangement eliminates the need for separate cooling system controls and reduces overall system weight while maintaining effective cooling of the lubricating liquid.
Solution Approach 2:
By integrating the cooling fan with the alternator assembly and positioning the heat exchanger within the alternator housing, the system achieves compact cooling functionality that reduces overall weight compared to a separate large heat exchanger installation.
3Temperature
If a relatively large heat exchanger is positioned in the bypass flow stream, then the cooling capability is improved, but the overall thrust output of the engine is reduced
Solution Approach 1:
The cooling fan acts as an intermediary device that creates a dedicated airflow path through the heat exchanger, independent of the propulsion fan bypass flow. This allows effective cooling to be achieved without blocking or interfering with the thrust-generating airflow, thereby maintaining engine thrust output.
Solution Approach 2:
The cooling system is segmented from the propulsion system by using the alternator shaft to drive the cooling fan separately. This creates an independent cooling airflow path that does not interfere with the bypass flow, allowing the heat exchanger to be positioned without reducing thrust output.
4Reliability
If a small permanent magnet alternator is used to power the engine controller, then the power supply reliability is improved, but the space occupied on the accessory gearbox increases
Solution Approach 1:
The alternator is integrated with the cooling fan assembly and positioned within the engine core structure rather than being mounted on the external accessory gearbox. This merging of functions and strategic positioning reduces the space required on the accessory gearbox while maintaining reliable power supply to the engine controller.
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 provides a reliable power supply to the engine controller, efficiently cools engine components, and reduces the overall weight and size of the gas turbine engine, while maintaining thrust output by integrating the alternator and cooling fan, allowing for a smaller, lighter system that can be positioned independently of the propulsion fan bypass flow.
Implementation Method 1
a cooling fan attached to the shaft and having fan blades positioned in the gas flow path for flowing air through the gas flow path, wherein the shaft is connected to and driven by the high pressure spool and the cooling fan is arranged to flow air over the heat exchanger
Implementation Method 2
a heat exchanger positioned in a gas flow path and fluidically connected to the gas turbine engine for cooling lubricating liquid used by the gas turbine engine
Implementation Method 3
a permanent magnet alternator for powering a gas turbine engine controller, the permanent magnet alternator comprising: a housing defining a portion of the gas flow path; a permanent magnet alternator stator attached to the housing; a shaft rotatable with respect to the housing; a permanent magnet alternator rotor attached to the shaft and positioned with respect to the permanent magnet alternator stator so as to generate electricity when the shaft rotates
Data Source
Figure 1
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AI summary
A permanent magnet alternator (42) includes a permanent magnet alternator stator (78) attached to a housing (64). A shaft (46) is rotatable with respect to the housing with a permanent magnet alternator rotor (76) attached to the shaft. The permanent magnet alternator rotor is positioned with respect to the permanent magnet alternator stator so as to generate electricity when the shaft rotates. A cooling fan (44) is also attached to the shaft and is positioned in a gas flow path (54) for flowing air through the gas flow path. The cooling fan (44) is arranged to flow air over a heat exchanger which is fluidically connected to a gas turbine engine lubrication circuit.