Gas Turbine Spool Coupling for In-Flight Start
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently starting and restarting, particularly during in-flight conditions, due to differences in starting requirements between ground-based and in-flight operations, which can lead to issues like rotor lock and dual flameout.
Innovation Solution
A spool coupling system that includes an electro-mechanical actuator and a clutch to mechanically link the low speed spool and the high speed spool, controlled by a system that determines the mode of operation and activates the spool coupling based on specific conditions to facilitate power transfer and prevent reengagement above a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spool coupling system is activated during in-flight operation to transfer power from low speed spool to high speed spool, then the in-flight start capability is improved, but the risk of rotor lock and dual flameout increases if activation occurs above the spool coupling activation condition
Solution Approach 1:
The controller monitors spool speeds and determines when to activate the spool coupling system based on specific parameters: the low speed spool must be below idle condition and the high speed spool must be above a threshold. These parameter thresholds define the safe activation envelope that prevents rotor lock and dual flameout while enabling in-flight starting
Solution Approach 2:
The controller continuously monitors the speeds of both low speed spool and high speed spool, and only activates the spool coupling system when specific speed conditions are met. This feedback mechanism ensures the system operates within safe parameters and prevents harmful conditions like rotor lock and dual flameout
2Adaptability or versatility
If the spool coupling system allows reengagement above the activation condition, then operational flexibility is improved, but the reliability deteriorates due to potential rotor lock and dual flameout
Solution Approach 1:
The spool coupling system dynamically adjusts its engagement state based on real-time spool speed conditions. The controller activates the coupling only when low speed spool is below idle and high speed spool is above threshold, and prevents reengagement when above activation condition, creating a dynamic safety envelope that adapts to changing operational conditions
Solution Approach 2:
The controller acts as an intermediary that mediates between the desire for operational flexibility and the need for safety. It monitors spool speeds and intelligently controls the spool coupling activation, allowing operation within safe envelopes while preventing harmful reengagement above activation conditions
3Speed
If the electro-mechanical actuator remains activated after clutch disengagement, then response time is improved, but the risk of unintended reengagement increases
Solution Approach 1:
The controller deactivates the electro-mechanical actuator in advance after the clutch disengages, ensuring that the actuator is not activated unless specific spool speed conditions are met. This preliminary deactivation prevents unintended reengagement while the controller maintains readiness to reactivate when conditions warrant
Solution Approach 2:
The controller continuously monitors spool speeds and uses this feedback to control the electro-mechanical actuator state. The actuator remains deactivated after clutch disengagement until the controller detects appropriate conditions, ensuring reliable control while maintaining operational readiness
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 spool coupling system enhances the in-flight start capability and reliability of gas turbine engines by ensuring efficient power transfer between spools, reducing the risk of rotor lock and dual flameout, and improving starter-assisted start capabilities.
Implementation Method 1
A spool coupling system includes an electro-mechanical actuator and a clutch configured to mechanically link the low speed spool and the high speed spool
Implementation Method 2
Engagement of the clutch and power transfer between the low speed spool and the high speed spool occurs based on activation of the electro-mechanical actuator
Data Source
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AI summary
A system includes a gas turbine engine 20;120 having a low speed spool 30 and a high speed spool 32. The system also includes a spool coupling system 70 configured to mechanically link the low speed spool 30 and the high speed spool 32. A controller 256 is operable to determine a mode of operation of the gas turbine engine, monitor for a spool coupling activation condition associated with the mode of operation, and activate the spool coupling system 70 based on the controller 256 detecting the spool coupling activation condition. Engagement and power transfer between the low speed spool 30 and the high speed spool 32 occurs based on activation of the spool coupling system 70 and reaching an engagement condition of the spool coupling system 70.