Segmented Carbon Piston Ring Seal for Turbine Leakage Control
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining effective seals between rotating parts to prevent wear and leakage, especially due to vibrational movements, which affect thermal and propulsive efficiencies.
Innovation Solution
A rotating seal assembly with annular sections and a retainer is used, where the annular sections have a radially-facing sealing surface and an annular slot, with a spring providing a biasing force to accommodate radial expansion and maintain a complete circumference seal, preventing hot airflow from passing through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal is disposed between relative rotating parts to prevent wear and leakage, then sealing effectiveness is improved, but the seal must accommodate vibrational movements and relative rotation which complicates the design and reduces reliability
Solution Approach 1:
The seal is divided into multiple separate annular sections (typically three) that can independently accommodate radial movements and vibrational displacements. Each section is retained on the shaft by a retainer and can move radially to maintain sealing contact, thereby reducing the complexity of designing a single complex seal mechanism while improving reliability through distributed sealing points
Solution Approach 2:
The seal sections are designed to be radially movable rather than fixed, allowing them to dynamically adjust to vibrational movements and relative rotation between the shaft and rotor. This dynamic capability enables the seal to maintain effective sealing contact under varying operational conditions without requiring complex adjustment mechanisms
2Duration of action of stationary object
If a seal is designed to accommodate wear through relative rotation, then durability is improved, but thermal and propulsive efficiencies deteriorate due to airflow leakage
Solution Approach 1:
Multiple seal sections create multiple sealing interfaces with the rotor, distributing the sealing function across several contact points. This segmentation maintains effective sealing to prevent hot airflow leakage (improving thermal efficiency) while each section can independently accommodate wear through radial movement (improving durability)
Solution Approach 2:
The seal sections can change their radial position parameter to maintain optimal sealing contact under varying conditions. By adjusting the radial distance from the shaft center, the seal sections adapt to wear and vibrational movements while maintaining consistent sealing effectiveness to prevent energy loss from airflow leakage
3Ease of manufacture
If a single continuous seal ring is used, then manufacturing is simplified, but the seal cannot accommodate radial expansion and vibrational movements
Solution Approach 1:
The seal is segmented into multiple independent annular sections that can be manufactured separately using standard machining processes, which is as simple as manufacturing a single ring. The segmentation then enables adaptability to radial expansion and vibrational movements, as each section can move independently while maintaining sealing contact
4Force
If the seal is made from carbon material to reduce wear, then friction is reduced, but the seal structure becomes more complex to retain and position
Solution Approach 1:
The carbon seal sections are divided into multiple small annular segments that can be retained by simple retainers on the shaft. The segmentation allows each carbon section to be independently positioned and retained, reducing the complexity of the retention structure compared to holding a single large carbon ring, while the carbon material continues to provide low-friction sealing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seal assembly effectively contains hot airflow and reduces wear on the shaft and rotor, enhancing engine performance by maintaining thermal and propulsive efficiencies.
Implementation Method 1
A retainer is disposed within the annular slot limiting radial expansion of the at least two annular sections
Implementation Method 2
the retainer comprises a spring that exerts a biasing force radially inward on the at least two annular sections
Implementation Method 3
Each of the at least two annular sections are separate parts and include a radially-facing sealing surface engaged to the radial inner sealing surface
Data Source
AI summary
A gas turbine engine assembly includes a compressor including a plurality of rotors, where at least one of the plurality of rotors includes a radial inner sealing surface. A rotating shaft drives rotation of the plurality of rotors, where the rotating shaft includes an annular groove proximate the radial inner sealing surface. A seal is disposed within the annular groove, and the seal comprises at least two annular sections forming a complete circumference. Each of the at least two annular sections are separate parts and include a radially-facing sealing surface engaged to the radial inner sealing surface of the rotor and an annular slot disposed radially inward of the radially-facing sealing surface. A retainer is disposed within the annular slot limiting radial expansion of the at least two annular sections.