Interdigitated Turbine Seal Assembly for Leakage Mitigation
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Solution Overview
Problem
Interdigitated gas turbine engines face significant deflection and gas leakage issues at rotary-to-rotary interfaces, which offset the performance and efficiency benefits of this arrangement due to larger deflections of rotary components compared to conventional engines with rotary-to-static seal assemblies.
Innovation Solution
The implementation of a rotating seal interface with a spring assembly and platforms between interdigitated turbine rotors, featuring teeth and abradable materials, allows for radial displacement and minimizes gaps between the rotors, thereby reducing deflection and leakage across these interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If interdigitated turbine rotor assemblies are used, then power and efficiency are improved, but deflection and gas leakage at rotary-to-rotary interfaces increase
Solution Approach 1:
A seal assembly is introduced as an intermediary component between the inner rotor and outer rotor to mitigate gas leakage. The seal assembly includes a seal element that contacts the rotor surface and a support structure that maintains the seal element's position, creating an effective barrier against gas leakage at the rotary-to-rotary interface while allowing the interdigitated configuration to maintain its power and efficiency benefits
2Power
If interdigitated turbine rotor assemblies are used, then power output is improved, but deflection at rotary interfaces increases
Solution Approach 1:
The seal assembly acts as a mediator between the two rotors, with the support structure providing mechanical stability. The support structure includes a first end coupled to the inner rotor and a second end coupled to the outer rotor, creating a stable framework that reduces relative deflection between the rotors while maintaining the power output benefits of the interdigitated configuration
Solution Approach 2:
The spring element in the seal assembly changes its mechanical properties (stiffness, preload) to compensate for deflections. By adjusting the spring constant and preload force, the seal assembly maintains optimal sealing contact despite variations in rotor deflection, thereby reducing gas leakage while preserving the dynamic performance benefits of the interdigitated arrangement
3Loss of energy
If rotary-to-rotary seal interfaces are implemented, then gas leakage is reduced, but device complexity increases
Solution Approach 1:
The seal assembly is segmented into distinct functional components: a seal element for preventing gas leakage, a support structure for maintaining position, and a spring element for providing preload. This segmentation allows each component to be optimized independently and simplifies maintenance and replacement, reducing the practical complexity despite adding functionality to reduce gas leakage
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 solution effectively mitigates deflection and gas leakage across rotary-to-rotary interfaces in interdigitated gas turbine engines, enabling the realization of counter-rotating turbine rotor benefits while maintaining efficient operation.
Implementation Method 1
The spring assembly permits displacement at least along the radial direction toward the first platform
Data Source
AI summary
The present disclosure is directed to a gas turbine engine including a turbine rotor assembly that includes a first turbine rotor and a second turbine rotor. The first turbine rotor includes an outer rotor and a plurality of outer rotors extended inwardly along a radial direction from the outer rotor. The second turbine rotor includes an inner rotor and a plurality of inner rotor airfoils extended outwardly along the radial direction from the inner rotor. The plurality of outer rotor airfoils and inner rotor airfoils are disposed in alternating arrangement along a longitudinal direction. One or more rotating seal interfaces are defined between the first turbine rotor and the second turbine rotor.