Split-Ring Seal Anti-Rotation Retention Block
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Solution Overview
Problem
Piston seals in gas turbine engines experience significant wear due to free circumferential rotation, leading to narrowing and shortening, which affects their sealing efficiency and longevity.
Innovation Solution
An anti-rotation device is introduced, comprising a retention block with a stem and boss that is inserted through a slot in a support structure's flange and groove, engaging the split-ring seal to limit its circumferential movement, thereby preventing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the split-ring seal is allowed to rotate freely, then the seal can accommodate thermal expansion and movement, but significant wear occurs leading to narrowing and shortening of the seal
Solution Approach 1:
A retention block is introduced as an intermediary component between the support structure and the split-ring seal. The retention block includes a stem that engages with the seal, preventing circumferential rotation while allowing axial movement for thermal expansion. This mediator resolves the contradiction by eliminating wear-causing rotation without restricting necessary seal movement.
Solution Approach 2:
The retention block is divided into functional segments: a stem portion that engages the seal to prevent rotation, and a boss portion that interfaces with the support structure. This segmentation allows each part to perform its specific function - the stem prevents harmful rotation while the boss provides structural anchoring, thereby improving seal reliability without causing additional constraints.
2Reliability
If a retention device is added to prevent rotation, then wear is reduced and seal lifespan is extended, but device complexity increases
Solution Approach 1:
The retention block combines multiple functions into a single component: it prevents circumferential rotation, allows axial thermal expansion, and interfaces with both the seal and support structure. By merging these functions into one integrated part rather than using separate components, the solution extends seal lifespan while minimizing the increase in device complexity.
Solution Approach 2:
The retention block serves multiple purposes simultaneously: it acts as a rotation preventer, a thermal expansion accommodator, and a structural connector. This multi-functionality reduces the need for additional components, thereby extending seal lifespan without proportionally increasing overall device complexity.
3Object-affected harmful factors
If the retention block is designed to engage the seal, then circumferential rotation is limited, but manufacturing precision requirements increase
Solution Approach 1:
The retention block features localized engagement surfaces with specific geometric properties optimized for their function. The stem has a cylindrical surface that matches the seal's groove, creating a simple radial interference fit that limits rotation without requiring high precision. The boss has a conical interface with the support structure that self-aligns during assembly, reducing the impact of manufacturing variations and minimizing the need for high precision across the entire component.
Data Source
AI summary
A method of limiting circumferential rotation of a split-ring seal for use in a gas turbine engine includes inserting a retention block through a slot in a flange of a support structure and into a groove configured to hold a split-ring seal, and engaging an end of a split-ring seal in the groove with a surface of the retention block.