Bowed Rotor Control System Using Periodic Electric Motor Rotation
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Solution Overview
Problem
Gas turbine engines face rotor and case bowing issues due to retained heat, which can lead to seal wear and potential engine stall if not addressed before restart, and existing pre-start rotation techniques are inefficient and time-consuming.
Innovation Solution
A bowed rotor prevention system that uses an electric motor and core turning controller to periodically rotate the rotor into specific positions based on previous positions, thermal temperature, and operating time, minimizing energy use and preventing excessive bowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is continuously rotated during pre-start to remove thermal bowing, then rotor bowing is effectively prevented, but energy consumption increases and start-up time is extended
Solution Approach 1:
The system implements periodic rotation of the rotor at predetermined intervals during the pre-start period, rather than continuous rotation. The controller receives input signals representing elapsed time and activates the rotation device only at specific intervals, allowing the rotor to remain stationary between intervals. This periodic activation maintains bowing prevention effectiveness while significantly reducing energy consumption compared to continuous rotation.
2Reliability
If the rotor is continuously rotated during pre-start to remove thermal bowing, then rotor bowing is effectively prevented, but aircraft start-up time is extended
Solution Approach 1:
The system uses periodic rotation at optimized intervals rather than continuous rotation, reducing the total time the rotation device is active. The controller uses elapsed time signals to determine when rotation is needed, allowing parallel processing of other start-up functions during stationary intervals, thereby reducing overall start-up time while maintaining bowing prevention.
Solution Approach 2:
The system performs rotor rotation in advance during the pre-start period at optimized intervals, preparing the rotor for imminent start-up. The predetermined time intervals are calculated to achieve sufficient bowing removal before the aircraft actually needs to start, allowing other systems to complete their preparations simultaneously without extending critical path time.
3Productivity
If rotor positions are precisely controlled and monitored, then rotation efficiency is optimized, but system complexity increases
Solution Approach 1:
The system incorporates rotation sensors that detect rotor position and provide feedback signals to the controller. The controller uses this feedback information to determine when the rotor has reached predetermined positions and to control the duration of each rotation event. This feedback mechanism enables precise control of rotation timing and position, optimizing the effectiveness of thermal bowing removal while using simple binary state sensing rather than continuous complex monitoring.
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
Effectively prevents or minimizes rotor bowing, reducing energy consumption and ensuring quicker aircraft start-up times by optimizing rotor positioning during the pre-start rotation process.
Implementation Method 1
An electric motor, which is mechanically coupled to the drive shaft, rotates the drive shaft and, in turn, the rotor a predetermined number of times
Implementation Method 2
When turbine engines are shut down after operation, the retained heat in the core rises and creates a bow in the turbine rotor and engine case. The bowing phenomenon is referred to as 'rotor bowing' or 'thermal bowing.'
Data Source
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AI summary
A bowed rotor prevention system (100) includes a gas turbine engine (20), an electric motor (102), and a core turning controller (150) in signal communication with the electric motor (102). The gas turbine engine (20) includes a rotor that is rotatably coupled to a drive shaft (50). The electric motor (102) is rotatably coupled to a motor shaft (108), which is mechanically coupled to the drive shaft (50) so as to rotate therewith. The core turning controller (150) is configured to invoke an anti-rotor bowing mode, and to control the electric motor (102) to periodically rotate the rotor into a plurality of rotor positions during a given time period in response to invoking the anti-rotor bowing mode.