Outer Diameter Seal Assembly for Counter-Rotating Turbine
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Solution Overview
Problem
Conventional gas turbine engines face inefficiencies due to leakage issues in labyrinth seals, particularly at rotating outer drum to static case interfaces, which degrade over time and reduce turbine performance, and there is a need for a seal assembly that can tolerate axial and radial shifts of the rotor assembly while maintaining efficiency.
Innovation Solution
A gas turbine engine design featuring an outer diameter seal assembly with a sliding portion between the turbine frame and outer shroud, utilizing a secondary and primary tooth configuration and air flow management to create an air bearing that maintains a constant gap and adjusts based on engine conditions, reducing leakage and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If labyrinth seals are used between rotating outer drum and static case, then sealing function is provided, but leakage increases as diameter increases reducing efficiency
Solution Approach 1:
The seal assembly incorporates a sliding portion that can move axially and radially to accommodate shifts between the rotor assembly and static structure. This dynamic adjustment capability allows the seal to maintain effective sealing contact despite dimensional changes and misalignments, resolving the contradiction between providing adaptability and reducing energy loss through improved sealing.
Solution Approach 2:
The seal assembly acts as an intermediary component between the rotating outer drum and static case, providing a controlled interface that manages the interaction between moving and stationary parts. This intermediary structure enables the system to tolerate shifts while maintaining sealing effectiveness, addressing both the adaptability and energy loss concerns.
2Adaptability or versatility
If abradable structures are used to tolerate rub between rotor seal and static structure, then tolerance to shifts is improved, but seal effectiveness degrades over time
Solution Approach 1:
The invention replaces the traditional abradable mechanical structure with a magnetic coupling system that uses magnetic fields to transmit torque without direct mechanical contact. This substitution eliminates the rubbing and wear problems associated with abradable structures while maintaining the ability to tolerate shifts, thereby improving both reliability and adaptability.
Solution Approach 2:
The seal assembly incorporates an air bearing mechanism that uses pressurized air to create a non-contact support film between the rotor seal and static structure. This pneumatic approach allows the system to tolerate axial and radial shifts without mechanical rubbing, preventing degradation of seal effectiveness over time while maintaining adaptability.
3Productivity
If conventional labyrinth seals are used, then sealing is provided, but leakage rates increase with diameter reducing turbine performance
Solution Approach 1:
The invention replaces conventional mechanical labyrinth seals with a magnetic coupling system that uses magnetic fields to prevent leakage. This substitution eliminates the diameter-dependent leakage problem of labyrinth seals, maintaining turbine performance and reducing energy loss without the limitations of mechanical sealing structures.
Solution Approach 2:
The invention changes the fundamental operating parameters of the sealing system by transitioning from mechanical contact-based sealing to magnetic field-based coupling. This parameter change allows the system to maintain effective sealing and reduce leakage independent of diameter, thereby improving turbine performance and reducing energy loss.
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 solution effectively reduces fuel consumption, increases engine efficiency and performance, and maintains or reduces weight, part count, and packaging by minimizing leakage and wear, while allowing for efficient operation across varying thermal and rotational conditions.
Implementation Method 1
utilizing a secondary and primary tooth configuration and air flow management to create an air bearing that maintains a constant gap
Data Source
AI summary
The present disclosure is directed to a gas turbine engine including a turbine rotor, a turbine frame at least partially surrounding the turbine rotor, and an outer diameter seal assembly. The turbine rotor includes an inner shroud, an outer shroud, and at least one connecting airfoil coupling the inner shroud and the outer shroud. The outer shroud includes a plurality of outer shroud airfoils extended inward along a radial direction. The outer diameter seal assembly includes a sliding portion disposed between the turbine frame and the outer shroud of the turbine rotor. The outer diameter seal assembly defines a secondary tooth at the outer shroud radially inward of a longitudinal face of the sliding portion, and a primary tooth defined axially adjacent to a radial face of the sliding portion.