Multi-Engine Gas Turbine Motoring Coordination
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Solution Overview
Problem
Gas turbine engines often experience a 'bowed rotor' condition due to thermal expansion after shutdown, which can lead to resonance and damage during restart, and existing methods for mitigating this condition are inefficient, especially when dealing with multiple engines simultaneously.
Innovation Solution
A system and method for multi-engine coordination that determines a motoring mode based on engine temperatures and performance parameters, allowing for coordinated dry motoring to gradually reduce rotor speed and prevent resonance, using a starter air valve to control the rotor speed and dynamically adjust the dry motoring profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motoring is performed separately for each engine at different times, then the bowed rotor condition is mitigated, but the total start time for a multi-engine aircraft is extended
Solution Approach 1:
The patent combines the motoring operations of multiple engines into a single coordinated process. The system enables simultaneous dry motoring of multiple engines by providing unified control and compressed air supply, allowing engines to be motored together rather than sequentially, thus reducing total start time while maintaining bowed rotor mitigation effectiveness
Solution Approach 2:
The control system provides multi-functional capability by managing both individual engine motoring and coordinated multi-engine motoring. The system can adaptively select between single-engine and multi-engine motoring modes based on operational requirements, making the system versatile for different starting scenarios
2Reliability
If a starter system drives rotation of a spool at a speed below critical speed for an extended period, then the bowed rotor condition is mitigated, but the engine start process is prolonged
Solution Approach 1:
The system dynamically adjusts the motoring speed and duration based on real-time engine conditions. The control system monitors engine parameters and adaptively modifies the motoring profile, allowing the spool to operate at variable speeds rather than a fixed low speed, thereby optimizing the balance between bowed rotor mitigation and start time
Solution Approach 2:
The patent changes the operational parameters of the motoring process by adjusting speed, duration, and air supply characteristics based on engine temperature and condition. The system transitions from static motoring parameters to dynamic parameter adjustment, enabling optimized motoring sequences that reduce overall duration while maintaining effectiveness
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 approach effectively mitigates the bowed rotor condition by allowing simultaneous dry motoring of multiple engines, reducing the risk of resonance and damage, and optimizing the engine start time by monitoring and adjusting the rotor speed to ensure safe and efficient engine restart.
Implementation Method 1
When the gas turbine engine of an airplane has been shut off for example, after an airplane has landed at an airport, the engine is hot and due to heat rise, the upper portions of the engine will be hotter than lower portions of the engine. When this occurs, thermal expansion may cause deflection of components of the engine which may result in a 'bowed rotor' condition.
Implementation Method 2
drive rotation of a spool within the engine for an extended period of time at a speed below which a resonance occurs (i.e., a critical speed or frequency) that may lead to damage when a sufficiently large bowed rotor condition is present
Data Source
AI summary
A system is provided for multi-engine coordination of gas turbine engine motoring in an aircraft. The system includes a controller operable to determine a motoring mode as a selection between a single engine dry motoring mode and a multi-engine dry motoring mode based on at least one temperature of a plurality of gas turbine engines and initiate dry motoring based on the motoring mode.