Split Piston Ring Seal Using Pressure Forces Against Centrifugal Load
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Solution Overview
Problem
Existing piston ring seals in gas turbine engines face challenges in supporting centrifugal forces, leading to inhibited axial movement due to large centrifugal forces and insufficient pressure difference across the seal, resulting in potential leakage.
Innovation Solution
A split piston ring seal design with a seal groove and a split piston ring seal configuration, where air pressure differences between adjacent rotor compartments produce axial and radial forces that counteract centrifugal forces, allowing for improved axial movement and sealing efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piston ring seal is used to seal between tie shaft and rotor disc, then sealing between adjacent cavities is achieved, but axial movement is undesirably inhibited due to large centrifugal forces
Solution Approach 1:
The piston ring seal is divided into two separate lateral members (first and second lateral members) connected by a center member, creating a split ring structure. This segmentation allows each lateral member to independently respond to pressure differentials and centrifugal forces, maintaining sealing contact while permitting necessary axial movement of the tie shaft relative to the rotor disc.
Solution Approach 2:
The seal structure changes its radial position parameter dynamically in response to pressure differentials across the seal. The pressure differential causes the seal to move radially inward or outward, allowing it to maintain sealing contact under varying centrifugal forces while still permitting axial movement. This parameter change enables the seal to adapt to different operating conditions.
2Stability of the object's composition
If the piston ring seal transfers centrifugal force to the rotor disc radially outboard, then the seal structure is stabilized, but the centrifugal force is large enough to inhibit axial movement
Solution Approach 1:
The split ring structure with separate lateral members allows differential movement and force distribution. Each lateral member can independently manage the transfer of centrifugal forces to the rotor disc while maintaining overall structural stability. This segmentation prevents the entire seal from being rigidly constrained, allowing limited axial movement while still providing stable force transfer.
3Reliability
If air pressure difference across the seal is insufficient, then the seal structure is simpler, but leakage occurs due to inability to counteract centrifugal forces
Solution Approach 1:
The seal utilizes changes in radial position as a parameter to enhance sealing efficacy. By moving radially in response to pressure differentials, the seal maintains optimal contact pressure with the rotor disc surface, counteracting centrifugal forces and preventing leakage without requiring excessively large pressure differentials across the seal.
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 design effectively mitigates centrifugal force effects by leveraging pressure differences to enhance the piston ring seal's ability to move axially and maintain sealing, reducing frictional forces and potential leakage.
Implementation Method 1
air is disposed in the FRC at a pressure P1 and air is disposed the SRC at a pressure P2, where P2 is greater than P1. The split piston ring seal is configured such that air disposed in the FRC at P1 produces a first axial force (FAF) acting on the split piston ring seal, and air disposed in the SRC at P2 produces a second axial force (SAF) acting on the split piston ring seal
Implementation Method 2
the piston ring seal is a split ring, which cannot support its own weight under expected centrifugal loading and therefore must transfer that force to the rotor disc radially outboard of the piston ring seal. In some applications, the centrifugal force acting on the piston ring seal is large enough that axial movement of the piston ring seal is undesirably inhibited
Implementation Method 3
The first lateral member is configured for engagement with the inner rotor surface... The split piston ring seal is configured such that air disposed in the FRC at P1 produces a first radial force (FRF) acting on the split piston ring seal, and air disposed in the SRC at P2 produces a second radial force (SRF) acting on the split piston ring seal
Data Source
AI summary
A gas turbine engine rotor assembly is provided that includes a shaft, a rotor, and a seal assembly. The seal assembly is configured to seal between a first and second rotor compartments on opposite sides of the seal assembly. The seal assembly includes a seal groove and a split piston ring seal. The split piston ring seal is configured such that air in the first rotor compartment at P1 produces a radial force acting on the split piston ring seal, and air in the second rotor compartment at P2 produces a second force acting on the split piston ring seal, wherein the second force is directed radially inward and the first force is directed radially outward, and the second force is greater than the first force.