Dual-Spool Accessory Gearbox Layout for Lower Mass and Case Loads
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Solution Overview
Problem
Existing turbine engines with dual spool power extraction and/or power injection face challenges with large accessory gearboxes that complicate fan blade-off case load management, maintainability, and gearbox strength, while also increasing mass and requiring complex oil and coolant systems.
Innovation Solution
The implementation of two separate gearboxes, one for high spool and one for low spool, with optimized spur gear spacing and positional arrangements, allowing for modular assembly as a line removable unit (LRU), independent oil and coolant systems, and vibration isolation, reducing overall mass and improving dynamic load management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single large accessory gearbox is used to accommodate dual mechanical offtakes from high and low spools, then all accessories can be integrated into one gearbox, but the gearbox size increases, complicating fan blade-off case load management, maintainability, and gearbox strength while increasing mass
Solution Approach 1:
The single large accessory gearbox is divided into two separate gearboxes: a high spool gearbox and a low spool gearbox. Each gearbox is sized appropriately for its specific spool's power extraction requirements, reducing the total mass compared to a single large gearbox while maintaining the capability to drive all necessary accessories through independent mechanical offtakes
2Adaptability or versatility
If a single large accessory gearbox is used to accommodate dual mechanical offtakes, then all accessories can be integrated, but fan blade-off case punch loads increase due to concentrated mass and structural requirements
Solution Approach 1:
By segmenting the accessory drive system into two separate gearboxes mounted at different locations on the fan case, the concentrated mass and structural load concentrations are eliminated. The fan blade-off loads are distributed across two separate mounting locations rather than concentrated in one large gearbox assembly
Solution Approach 2:
The two gearboxes are positioned at different angular locations around the fan case periphery, distributing the mechanical loads across different spatial dimensions. This dimensional distribution reduces the peak case punch loads at any single location compared to a centralized single gearbox configuration
3Adaptability or versatility
If a single large accessory gearbox is used, then a complex oil and coolant system is required to service the entire gearbox, but this increases system complexity and maintenance requirements
Solution Approach 1:
The lubrication and cooling systems are segmented into separate independent systems for the high spool gearbox and low spool gearbox. Each gearbox has its own oil supply, filtration, and cooling arrangements, eliminating the need for a single complex distribution system that would serve a large integrated gearbox
4Adaptability or versatility
If a single large accessory gearbox is used, then all accessories are integrated, but maintainability deteriorates due to larger size and more complex internal structure
Solution Approach 1:
The accessory drive system is segmented into two smaller, simpler gearboxes that are easier to access, disassemble, and maintain. Each gearbox has fewer internal components and a smaller overall size, making routine maintenance and repairs more straightforward compared to a single large complex gearbox
Data Source
AI summary
A system includes a turbine engine, a low spool gearbox, a high spool gearbox, and an interlink mechanically coupling the low spool gearbox to the high spool gearbox. The turbine engine includes a low-pressure spool and a high-pressure spool. The low spool gearbox is disposed within a core compartment of the turbine engine. The low spool gearbox is configured to transfer mechanical power between the low-pressure spool and a first accessory. The high spool gearbox is disposed within the core compartment of the turbine engine. The high spool gearbox is configured to transfer mechanical power between the high-pressure spool and a second accessory.