Hydrostatic Face Seal Anti-Fouling Design
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Solution Overview
Problem
Labyrinth seals in gas turbine engines deteriorate over time due to thermal and mechanical growths, assembly tolerances, and engine loads, leading to increased parasitic losses and thermodynamic cycle losses, and existing hydrostatic face seals are susceptible to fouling by debris.
Innovation Solution
The implementation of hydrostatic face seals with anti-fouling provisions, including a biasing member on the lower-pressure side and a shielded air bearing supply channel with a straight-through design to prevent debris accumulation, which positions the seal face relative to the seal runner and discourages debris entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If labyrinth seals are used to maintain pressure differentials, then pressure differentials are maintained, but the seals deteriorate over time due to thermal and mechanical growths, assembly tolerances, and engine loads, leading to increased parasitic losses and thermodynamic cycle losses
Solution Approach 1:
The patent replaces the mechanical contact-based labyrinth seal system with a hydrostatic face seal system that uses fluid pressure to maintain the seal. The hydrostatic seal uses pressurized air or gas to create a film between the seal face and seal runner, eliminating direct mechanical contact and wear, thereby resolving the contradiction between maintaining pressure differentials and preventing seal deterioration.
Solution Approach 2:
The patent employs pneumatic principles by using compressed air supplied through air bearing supply channels to create a hydrostatic air film between the seal face and seal runner. This pneumatic cushion maintains the pressure differential while preventing mechanical contact and deterioration, directly addressing the energy loss issue caused by deteriorating mechanical seals.
2Reliability
If hydrostatic face seals are used to maintain pressure differentials, then pressure differentials are maintained, but the seals are susceptible to fouling by debris
Solution Approach 1:
The patent applies preliminary anti-action by positioning the air bearing supply channel inlet on the downstream side of the seal face, creating a protective air curtain that prevents debris from reaching and fouling the seal interface before contamination can occur. This proactive measure protects the seal performance from debris-related deterioration.
Solution Approach 2:
The patent introduces pressurized air as an intermediary substance that forms a protective film between the seal face and the environment, preventing direct contact between the seal interface and debris. This intermediary air layer acts as a barrier that maintains seal performance while blocking harmful debris particles.
3Productivity
If air bearing supply channels are exposed to allow airflow, then consistent airflow is maintained for sealing, but debris can enter and foul the channel
Solution Approach 1:
The patent positions the air bearing supply channel inlet downstream of the seal face, creating a protective arrangement where the pressurized air flow moves away from the inlet opening. This preliminary anti-action prevents debris from entering the channel while maintaining consistent airflow, as the air pressure gradient directs flow away from potential contamination sources.
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
This configuration reduces the likelihood of seal fouling and maintains effective pressure differentials, minimizing parasitic losses and thermodynamic cycle losses by preventing debris from entering the air bearing supply channel and ensuring consistent airflow.
Implementation Method 1
a face seal having an air bearing supply channel extending from the high-pressure side to a side on which the seal face is located
Implementation Method 2
a biasing member, the biasing member being located on the lower-pressure side of the seal and being operative to bias the carrier such that interaction of the biasing member and gas pressure across the seal causes the carrier to position the seal face relative to the seal runner
Data Source
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AI summary
Gas turbine engine systems involving hydrostatic face seals (22) with anti-fouling provisioning are disclosed. In this regard, a representative turbine assembly for a gas turbine engine comprises: a turbine (120) having a hydrostatic seal (10); the hydrostatic seal (10) having a seal face (24), a seal runner (26), a carrier (20), and a biasing member (30); the seal face (24) and the seal runner (26) defining a high-pressure side and a lower-pressure side of the seal; the carrier (20) being operative to position the seal face (24) relative to the seal runner (26); and the biasing member (30) being located on the lower-pressure side of the seal and being operative to bias the carrier (20) such that interaction of the biasing member (30) and gas pressure across the seal causes the carrier (20) to position the seal face (24) relative to the seal runner (26).