Front Support Bearing Layout for Gas Turbine Gear Alignment
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Solution Overview
Problem
Geared architectures in gas turbine engines face challenges that reduce efficiency gains due to disrupted gear alignment caused by operational loads, necessitating improved support structures.
Innovation Solution
A gas turbine engine design featuring a forward and aft fan bearing system, with fixed outer races relative to the fan hub and inner races fixed to the engine static structure, supports the epicyclic gear system to maintain alignment and reduce misalignment forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an epicyclical gear assembly is used to drive the fan section at reduced speed, then propulsive efficiency is improved, but gear alignment is disrupted by operational loads
Solution Approach 1:
The patent employs dynamic bearing support structures that allow controlled movement and adjustment of gear components during operation. The bearing assembly includes elements that can accommodate thermal expansion and load-induced displacements while maintaining proper gear mesh alignment, thus preserving manufacturing precision under dynamic operating conditions.
Solution Approach 2:
The patent utilizes parameters such as bearing preload, clearance adjustments, and thermal compensation to maintain optimal gear alignment. By carefully controlling these parameters, the system compensates for load-induced misalignment and maintains the precision required for efficient gear operation throughout the engine's operational range.
2Productivity
If the fan section rotates at a different speed than the turbine section, then overall propulsive efficiency increases, but complex support structures are required to accommodate the speed reduction device
Solution Approach 1:
The bearing assembly is designed to perform multiple functions simultaneously: supporting radial and axial loads, accommodating thermal expansion, maintaining gear alignment, and allowing for speed reduction. This multi-functional design reduces the need for separate specialized components, thereby simplifying the overall support structure while maintaining the required speed reduction capability.
Solution Approach 2:
The patent combines the speed reduction function with the bearing support function into an integrated assembly. The epicyclical gear assembly is directly coupled with the bearing structure, eliminating the need for separate mounting structures and reducing overall complexity. This merging of functions maintains propulsive efficiency while simplifying the support structure.
Data Source
AI summary
A gas turbine engine may include a propulsor section including a propulsor having propulsor blades extending from a propulsor hub. A speed reduction device interconnects a turbine and a propulsor shaft that drives the propulsor. Bearings are positioned on opposite sides of the speed reduction device. A propulsor drive gear module is also disclosed.