Embedded Electrical Machine Cooling in Gas Turbine Engines
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Solution Overview
Problem
Gas turbine engines face challenges in managing high temperatures, particularly affecting embedded electrical machines located in the aft portion, which can be exposed to exhaust gases exceeding 700°C, necessitating effective cooling solutions to maintain operational efficiency and accessibility.
Innovation Solution
A cooling system is implemented within the gas turbine engine that includes an enclosure defining multiple cooling airflow paths and buffer cavities around the electrical machine, coupled with a cooling duct and blower assembly to manage temperature, ensuring the electrical machine remains within a desired temperature range during operation and shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrical machine is located inward of the core airflow path to improve compactness, then the temperature exposure increases, but accessibility for maintenance deteriorates
Solution Approach 1:
The cooling system is segmented into multiple independent airflow paths: a first cooling airflow path that provides cooling air to the electrical machine, and a second cooling airflow path that is isolated from the electrical machine. This segmentation allows targeted cooling of the electrical machine without interfering with the compact internal arrangement.
Solution Approach 2:
A thermal barrier or insulation structure acts as an intermediary between the electrical machine and the hot exhaust gases. The barrier physically separates the electrical machine from the harmful thermal environment, allowing the machine to be positioned in a compact location while still protecting it from excessive temperature exposure.
2Reliability
If a cooling system is added to protect the electrical machine from high temperatures, then reliability improves, but device complexity increases
Solution Approach 1:
The cooling system is designed to serve multiple functions simultaneously: the first cooling airflow path cools the electrical machine during operation, the second cooling airflow path provides additional cooling or ventilation, and the system operates in coordinated fashion to maintain temperature control. This multi-functionality reduces the need for separate dedicated cooling components.
Solution Approach 2:
The cooling system utilizes the engine's own airflow resources to cool the electrical machine. By routing a portion of the engine's internal airflow through the first cooling airflow path, the system self-regulates temperature without requiring external cooling equipment or additional energy input.
3Productivity
If the electrical machine is embedded within the engine core, then productivity increases, but ease of repair deteriorates
Solution Approach 1:
The electrical machine is segmented from the main engine assembly through a removable mounting structure. This allows the electrical machine to be positioned within the compact engine core for high power density, while enabling independent removal and replacement of the electrical machine without disassembling the entire engine.
Solution Approach 2:
The mounting structure incorporates dynamic elements such as quick-release fasteners or bayonet connections that allow rapid installation and removal of the electrical machine. This dynamic connection system maintains the compact embedded arrangement during operation while providing easy accessibility for maintenance and replacement.
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 cooling system effectively maintains the electrical machine at a safe temperature, enhancing its operational reliability and facilitating easy maintenance by allowing access and replacement without disassembling the entire engine.
Implementation Method 1
A cooling duct provides pressurized air to the first cooling airflow path such that the air flows along both the first cooling airflow path and the second cooling airflow path
Data Source
AI summary
A gas turbine engine includes a fan located at a forward portion of the gas turbine engine. A compressor section and a turbine section are arranged in serial flow order. The compressor section and the turbine section together define a core airflow path. A rotary member is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. An electrical machine is coupled to the rotary member and is located at least partially inward of the core airflow path in a radial direction. An enclosure at least partially encloses the electrical machine. The enclosure at least partially defines a first cooling airflow path within the enclosure that at least partially defines a first cooling airflow buffer cavity at least partially around the electrical machine. The first cooling airflow path is in communication with a second cooling airflow path located outside the enclosure that at least partially defines a second cooling airflow buffer cavity at least partially around the enclosure. A cooling duct provides pressurized air to the first cooling airflow path such that the air flows along both the first cooling airflow path and the second cooling airflow path providing the first cooling airflow buffer cavity and the second cooling airflow buffer cavity.