Selective Spool-to-Spool Transmission for Lower Idle Fuel Flow
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Solution Overview
Problem
Turbine engines face inefficiencies in providing power to aircraft systems, particularly during ground idle conditions, leading to increased fuel flow and thrust levels that affect compressor stability and maintenance costs.
Innovation Solution
A transmission system with a speed changing element, power transfer clutch, and accessory clutch is used to selectively transfer power between pressure spools of the turbine engine, allowing for efficient power distribution to accessories and spools, reducing idle thrust and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If shaft power is extracted from the high spool during ground operation, then power is provided for aircraft operation, but fuel flow increases and compressor stability margin decreases
Solution Approach 1:
The patent employs a transmission system with variable gear ratios that dynamically adjusts the connection between the high spool and accessories based on operating conditions. During ground idle, the transmission disconnects or reduces the load on the high spool, allowing it to operate at optimal speed without the energy penalty of powering accessories, thereby reducing fuel flow while still providing necessary power when needed.
Solution Approach 2:
The transmission system segments the power flow path by introducing separate clutch mechanisms (power transfer clutch and accessory clutch) that can independently engage or disengage specific power paths. This allows selective extraction of power from the high spool only when necessary, rather than continuous extraction that would increase fuel consumption during idle operations.
2Power
If shaft power is extracted from the high spool during ground operation, then power is provided for aircraft operation, but compressor stability margin decreases
Solution Approach 1:
The transmission system dynamically adjusts the load on the high spool based on operational requirements. During ground idle conditions, the transmission disconnects the accessory load from the high spool, allowing the compressor to operate at stable idle speeds without the destabilizing effect of variable accessory loads, thereby maintaining compressor stability margin while still enabling power extraction when needed.
Solution Approach 2:
The transmission system acts as an intermediary between the high spool and accessories, providing a buffer that isolates the compressor from direct accessory loads. The clutch mechanisms and gearset mediate the power transfer, allowing the high spool to maintain stable operation while still delivering power to accessories when required, thus preserving compressor stability margin.
3Power
If the transmission operates in first configuration to power the accessory, then the accessory receives power, but power transfer from the first pressure spool to the second pressure spool is prevented
Solution Approach 1:
The transmission system is designed with dynamic clutch control that can switch between configurations based on operational demands. The control system monitors engine conditions and selectively engages the power transfer clutch or accessory clutch, allowing the system to adapt between powering the accessory and transferring power between spools as needed, thereby maintaining versatility while providing dedicated power paths.
4Power
If the transmission operates in second configuration to transfer power from the first pressure spool to the second pressure spool, then power is transferred between spools, but accessory power is prevented
Solution Approach 1:
The transmission system employs dynamic clutch control that can switch between configurations based on operational demands. The control system monitors engine conditions and selectively engages the power transfer clutch or accessory clutch, allowing the system to adapt between powering the accessory and transferring power between spools as needed, thereby maintaining versatility while providing dedicated power paths.
Data Source
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AI summary
A transmission (30) operatively connected to a turbine engine of an aircraft to selectively transfer power from a first pressure spool (75) of the turbine engine to a second pressure spool (85) of the turbine engine and to power an accessory (60). The transmission is configured to selectively operate in one of a first configuration and a second configuration. The first configuration transfers power from the turbine engine to the accessory and the second configuration transfers power from the first pressure spool to the second pressure spool.