Compressor Rotor Rotation via Pressurized Airflow During Shutdown
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Solution Overview
Problem
During engine shutdown, the asymmetrical thermal expansion of compressor rotors due to heat stratification leads to a bowed-rotor condition, where the top rotor contacts the casing, potentially causing damage upon startup.
Innovation Solution
A pressurized airflow system is introduced to rotate and cool the compressor rotors by injecting pressurized air through nozzles or stator vanes, mitigating the bowed-rotor condition by ensuring uniform cooling and preventing contact with the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is shut down, then the engine stops operating, but heat stratification causes asymmetrical thermal expansion of compressor rotors leading to bowed-rotor condition
Solution Approach 1:
The system introduces pressurized airflow to rotate the compressor rotor before shutdown to pre-distribute cooling airflow throughout the compressor section. This preliminary action ensures uniform temperature distribution and prevents bowed-rotor condition from developing during the shutdown period.
Solution Approach 2:
The pressurized airflow system maintains continuous rotor rotation and cooling airflow delivery even after engine shutdown. This continuous action ensures uniform cooling persists throughout the shutdown period, preventing thermal stratification and maintaining rotor alignment.
2Reliability
If pressurized airflow is injected to rotate the compressor, then uniform cooling is achieved, but additional system complexity is introduced
Solution Approach 1:
The system uses the engine's own pressurized air supply system to provide cooling airflow during shutdown. By utilizing existing engine resources (compressed air storage and delivery infrastructure), the system avoids adding external complex cooling equipment while achieving the desired rotor cooling and rotation.
Solution Approach 2:
The pressurized airflow system serves multiple functions: it rotates the compressor rotor to distribute cooling uniformly, provides direct cooling to the rotor surfaces, and maintains airflow through the compressor stages. This multi-functionality reduces the need for separate dedicated cooling systems.
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 system effectively mitigates the bowed-rotor condition by maintaining rotor alignment and providing uniform cooling, reducing the risk of damage during engine startup.
Implementation Method 1
direct the flow of pressurized air onto the rotor vanes of the compressor rotor shaft assembly, thereby causing the compressor rotor shaft assembly to rotate
Implementation Method 2
injects a pressurized airflow into a compressor section of a gas turbine engine to rotate and to cool the compressor rotors
Data Source
AI summary
A gas turbine engine includes a compressor section with a compressor rotor shaft assembly including a plurality of compressor rotors longitudinally spaced apart from each other via respective ones of a plurality of shaft sections of a rotor shaft, each compressor rotor of the plurality of compressor rotors having a plurality of rotor vanes extending radially outward therefrom and being circumferentially spaced about the compressor rotor. A stator shroud assembly has a stator shroud casing surrounding the compressor rotor shaft assembly, a compressor flow passage being defined between the compressor rotor shaft assembly and the stator shroud casing. A pressurized air source generates a flow of pressurized air to be provided to the compressor section, and a plurality of pressurized airflow nozzles are connected with the pressurized air source and provide the flow of pressurized air into the compressor flow passage to cause the compressor rotor shaft assembly to rotate.