Decoupled Power Turbine Gear Layout for Stable Heat-Recovery Engines
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Solution Overview
Problem
Long shafts in gas turbine engines with nested shaft architectures face rotor dynamic stability challenges and complicate engine architectures, inhibiting the implementation of desirable features like heat recovery systems.
Innovation Solution
Aircraft turbine engines with a decoupled power turbine driving a propulsive fan through a speed change gearbox, featuring a support structure with fairings and multiple gearboxes to stabilize rotor dynamics and provide space for additional systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a long shaft is used to connect the core engine to the propulsive fan in a nested shaft architecture, then the engine can achieve compact layout, but rotor dynamic stability deteriorates and additional bearing structures are required
Solution Approach 1:
The patent divides the power transmission system into separate functional modules: the core engine, a decoupled power turbine, and a fan drive gear system. This segmentation eliminates the need for a long nested shaft by using a decoupled architecture where the power turbine is mechanically independent from the core engine, thereby improving rotor dynamic stability while maintaining compact layout through optimized component arrangement.
2Volume of moving object
If a long shaft is used in nested shaft architecture, then compact layout is achieved, but device complexity increases due to additional bearing structures
Solution Approach 1:
By segmenting the power transmission system into a decoupled power turbine and fan drive gear system, the patent eliminates the need for additional bearing structures that would be required to support a long nested shaft. The decoupled architecture allows each component to be independently supported, reducing overall device complexity.
3Stability of the object's composition
If a decoupled power turbine with long shaft is used, then heat recovery system integration is inhibited, but rotor dynamic stability can be improved
Solution Approach 1:
The patent repositions the power turbine and fan drive gear system in a spatial arrangement that creates available volume within the nacelle. The decoupled power turbine is positioned with its shaft extending through the nacelle, and the fan drive gear system is mounted on a support structure that utilizes the vertical and lateral dimensions of the nacelle space, thereby creating room for heat recovery system integration while maintaining rotor dynamic stability.
4Adaptability or versatility
If power turbine shaft speed is reduced through gear system, then heat recovery system integration is enabled, but device complexity increases
Solution Approach 1:
The fan drive gear system serves multiple functions: it reduces the power turbine shaft speed to match the fan's operational requirements, transmits power from the decoupled power turbine to the fan, and provides structural support for mounting the heat recovery system. By making the gear system multi-functional, the patent enables heat recovery integration without proportionally increasing device complexity.
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
Improves rotor dynamic stability and enables the integration of heat recovery systems by reducing power turbine shaft speed and providing additional space for engine components.
Implementation Method 1
the gas flow from the core engine is expanded through the power turbine to generate shaft power
Implementation Method 2
a heat recovery system that is at least partially supported by at least one of the support structure and the nacelle
Data Source
AI summary
A propulsion system for an aircraft includes a propulsor section that includes a fan with a plurality of fan blades that are rotatable about a fan axis, a core engine that is configured to generate a gas flow, a power turbine that is mechanically uncoupled from the core engine and rotatable independent of the core engine, the gas flow from the core engine is expanded through the power turbine to generate shaft power, a support structure where the power turbine is mounted relative the core engine, a fan drive gear system that is driven by the power turbine and at least partially mounted to the support structure, and a power turbine shaft that includes a first coupling to the fan drive gear system and a second coupling to the propulsor section.