Adjustable Under-root Spacer for Gas Turbine Fan Blade Load Consistency
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Solution Overview
Problem
Existing under-root spacers in gas turbine engines experience load variation across different fan blade circumferential locations due to manufacturing tolerances, leading to inconsistent loads and root wear, which is undesirable for preventing movement within the slot.
Innovation Solution
A spacer with first and second portions that cooperate to provide discrete height settings, allowing for adjustable radial heights, is inserted beneath the root to ensure consistent loads across varying tolerance stack-ups, featuring a contoured first portion and a pivotally secured second portion with adjustable tabs for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed-height under-root spacer is used, then the device complexity is reduced, but load consistency across different fan blade circumferential locations deteriorates due to manufacturing tolerances
Solution Approach 1:
The spacer is divided into multiple discrete height segments that can be selectively engaged. Each segment represents a different radial height setting, allowing the spacer to be customized for specific tolerance conditions while maintaining a relatively simple overall structure.
Solution Approach 2:
The spacer transitions from a static fixed-height design to a dynamic adjustable-height design. The ability to select different height settings allows the spacer to adapt to varying manufacturing tolerances across different circumferential locations, improving load consistency without significantly increasing structural complexity.
2Reliability
If an adjustable spacer with multiple height settings is used, then load consistency across circumferential locations is improved, but device complexity increases
Solution Approach 1:
The spacer employs segmented height settings achieved through discrete tabs or engagement features at different radial positions. This segmentation allows for adjustable height without requiring a completely complex reconfigurable structure, balancing adaptability with structural simplicity.
Solution Approach 2:
The adjustment mechanism is localized to specific regions of the spacer where height variation is needed. Rather than making the entire spacer complex, only the necessary portions are designed with adjustment capabilities, minimizing overall structural complexity while achieving the desired load consistency.
3Device complexity
If manufacturing tolerances are tightened to eliminate the need for adjustment, then device complexity is reduced, but manufacturing cost and difficulty increase
Solution Approach 1:
Instead of tightening manufacturing tolerances to eliminate clearance variations, the invention changes the operational parameter of the spacer by providing multiple height settings. This allows the system to accommodate normal manufacturing tolerances while maintaining proper fit and load distribution.
Solution Approach 2:
The adjustable spacer acts as an intermediary element between the slot and the root, compensating for manufacturing tolerance variations. Rather than requiring extremely precise manufacturing, the spacer provides the necessary adjustment to achieve proper fit and function.
Data Source
AI summary
A gas turbine engine rotor includes a hub having a slot. A blade includes a root received in the slot. An under-root area is provided between the root and the fan hub in the slot. A spacer includes first and second portions that cooperate with one another to provide an adjustment feature with discrete height settings. The adjustment feature provides different radial heights of the spacer. The spacer is arranged in the under-root area beneath the root.