T-Bolt Fastener for Turbine Nozzle Liner Bracket
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Solution Overview
Problem
The existing methods for attaching a bracket and liner to convergent flaps and seals in a gas turbine engine nozzle are cumbersome and prone to leakage, as they require reaching both sides of large components and often necessitate permanent staking due to the difficulty in accessing threaded fasteners around the engine's circumference.
Innovation Solution
A t-bolt with a washer and spring fingers is used to secure the liner to the convergent flaps and seals, allowing the bolt to be inserted and turned 90°, with the washer held in place by spring fingers to prevent rotation and leakage, enabling assembly from within the nozzle without needing to access both sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional threaded fasteners with sheet metal tabs or rivets are used to secure the bracket to the flap and seal, then the bracket can be attached to the flaps and seals, but the installation becomes cumbersome and replacement becomes difficult due to the need to reach both sides of large components
Solution Approach 1:
The fastening structure is divided into separate functional components: a bolt with head on one side, a nut on the other side, and a washer with legs in between. This segmentation allows each component to be optimized for its specific function and enables assembly from a single location without needing to access both sides of the large components.
Solution Approach 2:
The washer with legs acts as an intermediary element between the bolt and the flap/seal structure. The legs extend into the slot to engage with spring fingers, providing a mechanism that eliminates the need to reach both sides of the components while maintaining secure attachment.
2Ease of operation
If openings, slots, or other structures are created to facilitate threaded fastener attachment, then the fastener can be accessed and tightened, but these structures create potential leakage paths for products of combustion
Solution Approach 1:
The fastening mechanism is extracted from the traditional threaded hole configuration and repositioned to utilize the existing slot structure. The bolt inserts through the slot rather than requiring threaded openings, and the washer with legs engages within the slot to prevent rotation, eliminating the need for additional openings that would create leakage paths.
Solution Approach 2:
The slot serves multiple functions: it provides a passage for the bolt, contains the washer with legs to prevent rotation, and maintains the sealed structure of the flap and seal assembly. This multi-functionality eliminates the need for separate threaded openings while enabling fastener access.
3Ease of operation
If the bolt is inserted through a slot and turned 90° with the t-head resting against the outer side, then the bolt can be secured without reaching both sides, but the washer must be held in place to prevent rotation during tightening
Solution Approach 1:
The spring fingers automatically engage with the washer legs to hold the washer in place during assembly. This self-service mechanism eliminates the need for manual positioning or additional fastening steps to secure the washer, while ensuring reliable prevention of bolt rotation during tightening.
Solution Approach 2:
The washer is positioned in the slot with its legs extending forwardly before the bolt is inserted and tightened. The spring fingers are pre-positioned to engage with the washer legs, creating a pre-assembled unit that prevents rotation during the final tightening operation.
Data Source
AI summary
A quick change connection is provided for attaching a bracket and liner subassembly to convergent flaps and seals in an adjustable nozzle for a gas turbine engine. A threaded attachment member has a t-shaped head that is secured to prevent rotation by a washer. The washer is held in place in the convergent flaps and seals by spring fingers in a slot. By utilizing the washer, a simple threaded connection can be utilized even though the threaded attachment member must extend to a radially outer surface of the convergent flaps and seals, while a nut is threaded onto the threaded attachment member radially inwardly of the convergent flaps and seals. The washer prevents rotation of a head of the threaded attachment member, and thus allows the nut to be easily tightened to secure the components. This also facilitates maintenance as the threaded nut can be easily removed from the threaded attachment for replacement.