Embedded Gas Turbine Electric Machine With Annular Stator Cooling
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Solution Overview
Problem
Gas turbine engines face challenges in reducing weight and complexity while effectively cooling and securing embedded electric machines, which generate significant heat due to high rotational speeds, and require efficient lubrication and cooling systems to manage heat and torque.
Innovation Solution
The solution involves embedding the electric machine within the gas turbine engine frame, using an annular fluid passage created between the engine frame and the stator to direct a cooling fluid for heat removal, and employing positioning keys to secure the stator relative to the engine frame, reducing weight and complexity while maintaining effective cooling and electrical grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the electric machine is embedded within the gas turbine engine frame, then the overall weight and complexity are reduced, but the cooling efficiency must be maintained despite direct contact with hot combustion gases
Solution Approach 1:
The engine frame is merged with the cooling system by incorporating cooling channels directly into the frame structure. The frame simultaneously serves as structural support and heat dissipation pathway, eliminating the need for separate cooling components and reducing overall weight while maintaining cooling efficiency
Solution Approach 2:
A thermal barrier or insulating layer is introduced between the electric machine stator and the engine frame to prevent direct heat transfer from hot combustion gases. This intermediary protects the temperature-sensitive electric components while allowing the frame to maintain its structural and cooling functions
2Ease of manufacture
If the stator is secured to the engine frame using traditional fasteners, then the installation is straightforward, but the structural integrity and torque resistance are insufficient
Solution Approach 1:
The positioning keys integrate multiple functions into a single component: they provide mechanical interlocking for torque resistance, precise radial positioning for cooling channel alignment, and electrical grounding pathways. This merged design achieves high strength requirements while maintaining manufacturing simplicity
Solution Approach 2:
The stator assembly is segmented with integrated positioning keys that extend into corresponding slots in the engine frame. This segmentation creates discrete engagement points that distribute mechanical loads and provide precise positioning without requiring complex fastening systems
3Temperature
If cooling channels are introduced into the engine frame, then the cooling efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The engine frame is designed with multi-functionality, serving simultaneously as structural support, mounting platform, and heat dissipation system. The cooling channels are integrated into the frame's existing structural geometry, allowing the same component to perform multiple functions without adding separate cooling structures
Solution Approach 2:
The cooling channels utilize the natural thermal expansion and contraction parameters of the engine frame material. The channel dimensions and positioning are designed to accommodate thermal cycling, allowing efficient heat removal while maintaining structural integrity and simplifying manufacturing tolerances
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 reduces the overall weight and complexity of the gas turbine engine by integrating the electric machine, enhances cooling efficiency through direct heat transfer to the engine frame, and ensures secure installation and operation by utilizing the engine frame as both a housing and a heat sink, effectively managing heat and torque.
Implementation Method 1
The annular fluid passage is configured to direct a cooling fluid around the stator to remove heat from the stator
Implementation Method 2
A cooling fluid, such as cooling oil, may remove heat from the stator and transfer at least a portion of the removed heat away from the engine frame to a fluid circulation system
Implementation Method 3
Two or more positioning keys are positioned within the stator and the engine frame to tangentially position the stator around an axis of the engine frame and fix the stator to the engine frame
Implementation Method 4
an electric machine for converting electrical power to and/or from mechanical power, which includes a stator and a rotor
Data Source
AI summary
Gas turbine engines include an engine frame defining an inner radial surface, a shaft rotatably mounted in the engine frame along a longitudinal axis, and an electric machine that includes a rotor coupled to the shaft and a stator coupled to the engine frame and defining an outer radial surface. In some gas turbine engines, the engine frame includes inlet and outlet fluid passages, each extending to a portion of the inner radial surface. The portion of the inner radial surface of the engine frame is spaced from the outer radial surface of the stator to form an annular fluid passage around the stator of an electric machine. The annular fluid passage is configured to direct a cooling fluid around the stator to remove heat from the stator. Some gas turbine engines include two or more positioning keys configured to fix the stator relative to the engine frame.