Gas Turbine Generator Mounting for Stable Rotor-Stator Clearance
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Solution Overview
Problem
The increasing size of electric machines in aircraft gas turbine engines due to rising power demands poses packaging challenges within the limited space available, and existing arrangements are heavy, complex, and inefficient.
Innovation Solution
The electric machine rotor is mounted to the main engine spool, with the stator mounted to a moveable element of a damper, allowing for relative movement that maintains a consistent running clearance between the rotor and stator, reducing the risk of contact and enhancing efficiency, using a bearing arrangement with a static and moveable element, such as a squeeze film, elastomeric, or electromagnetic damper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric machine size is increased to meet rising power demands, then the power output is improved, but the packaging space required increases and becomes difficult to accommodate within the limited engine space
Solution Approach 1:
The electric machine is nested within the annular space radially inward of the compressor, with the stator positioned inside the compressor housing and the rotor rotating within this confined space. This nesting arrangement allows the electric machine to be accommodated within the existing engine structure without requiring additional external space, thereby resolving the contradiction between increased power output and limited packaging space
Solution Approach 2:
The electric machine utilizes the radial dimension within the compressor annular space, positioning the stator radially inward and the rotor rotating in the radial direction. This three-dimensional utilization of space within the existing engine envelope allows for high power density packaging without increasing the overall engine footprint
2Stability of the object's composition
If the stator is rigidly mounted to reduce movement, then the structural stability is improved, but the running clearance consistency deteriorates and rotor-stator contact risk increases
Solution Approach 1:
The stator is mounted to the moveable element of the damper, allowing it to move dynamically with the rotor during operation. This dynamic mounting arrangement maintains a consistent running clearance between the rotor and stator by accommodating relative movements, thereby preventing rotor-stator contact while preserving structural stability through the damper's controlled movement
Solution Approach 2:
The damper acts as an intermediary between the rigid engine structure and the electric machine stator. It provides a compliant mounting that allows controlled movement of the stator to maintain consistent clearance with the rotor, mediating between the need for structural stability and the need for reliable clearance maintenance
3Power
If conventional gear arrangements are used to transmit power, then the power transmission capability is improved, but the system weight and complexity increase
Solution Approach 1:
The invention extracts and eliminates the complex gear transmission system from the power train. The electric machine is directly coupled to the compressor shaft, removing the need for bevel gears, angle drive shafts, and other intermediary transmission components. This direct coupling maintains full power transmission capability while dramatically reducing system complexity and weight
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 configuration reduces the risk of rotor-stator contact, allowing for higher power density and efficiency, particularly in permanent magnet machines, and improves packaging efficiency by maintaining a consistent air gap, thereby addressing the space and weight challenges.
Implementation Method 1
a bearing arrangement configured to rotatably support the main engine spool, the bearing arrangement comprising a damper comprising a static element and a moveable element
Data Source
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AI summary
An aircraft gas turbine engine (10) comprises a main engine spool (22) and a bearing arrangement (36) configured to rotatably support the main engine spool (22). The bearing arrangement (36) includes a damper (41) comprising a static element (42) and a moveable element (39). The gas turbine engine further comprises an electric machine (30) comprising a rotor (34) and a stator (32). The rotor (34) is mounted to the main engine spool (22), and the stator (32) is mounted to the moveable element (39) of the damper to be moveable with the moveable element (39).