Inverted Non-Contacting Dynamic Seals for Gas Turbine Thrust Load Control
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Solution Overview
Problem
The challenge in gas turbine engine design is to control the net thrust load on the thrust bearing to ensure it remains below the allowable load limit, which affects the operational life and efficiency of the engine.
Innovation Solution
The implementation of non-contacting dynamic seals positioned adjacent to the outer and inner diameters of the spool to define secondary flow cavities, which affect the net thrust load by maximizing the annulus area and utilizing hydrodynamic principles to create a hydrodynamic film for sealing, thereby reducing the forward net thrust load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing methods are used, then sealing function is achieved, but thrust bearing load increases and operational life decreases
Solution Approach 1:
The patent replaces conventional mechanical contact seals with non-contacting dynamic seals that utilize hydrodynamic principles. The seal elements create a fluid film barrier that prevents gas leakage without mechanical contact, thereby eliminating the thrust load that would otherwise be imposed on the bearing by contact seal friction and reaction forces.
Solution Approach 2:
The patent employs hydrodynamic sealing where pressurized gas flows through specially designed seal element passages, creating a fluid dynamic barrier. The seal elements are configured with inlet and outlet passages that utilize gas pressure and flow to maintain a separating film, preventing leakage while avoiding mechanical contact and associated thrust loads on the bearing.
2Force
If non-contacting dynamic seals are positioned to maximize annulus area, then forward net thrust load is reduced, but seal system complexity increases
Solution Approach 1:
The patent inverts the conventional seal arrangement by positioning seal elements with their sealing surfaces facing outward toward the case rather than inward toward the rotor. This inverted configuration, combined with strategically positioned inlet and outlet passages, creates a hydrodynamic effect that generates a force opposing the forward thrust, thereby reducing the net thrust load on the bearing.
Solution Approach 2:
The patent applies different functional characteristics to different regions of the seal system. The seal elements have specific local features including inlet passages positioned to receive pressurized gas, outlet passages for gas discharge, and sealing surfaces with specific geometries. Each local region is optimized to contribute to the overall thrust reduction while maintaining sealing effectiveness.
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 effectively reduces the forward net thrust load, increases the operational life of the thrust bearing, and enhances engine efficiency by optimizing the thrust balance without compromising the thrust bearing life.
Implementation Method 1
utilizing hydrodynamic principles to create a hydrodynamic film for sealing
Data Source
AI summary
A gas turbine engine includes a first non-contacting dynamic rotor seal interfaced with a spool, the first non-contacting dynamic seal operates to seal adjacent to an outer diameter and a second non-contacting dynamic rotor seal with respect to the spool, the second non-contacting dynamic seal operates to seal adjacent to an inner diameter. A method of controlling a net thrust load on a thrust bearing of a gas turbine engine spool is also disclosed.