Angled Knife Edge Seal for Gas Turbine Thermal Fatigue
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Solution Overview
Problem
Current knife edge seal designs in gas turbine engines have a low fatigue life due to high temperatures and mechanical loads, necessitating an improved seal that can withstand increased thermal and mechanical stresses over a longer period.
Innovation Solution
A knife edge seal with a base and neck structure, where the neck has a reduced thickness, extending radially and axially at an angle from the aft hub, utilizing suitable temperature-resistant materials and an angled design to balance thermal and mechanical loads, decoupling thermal growth and reducing compressive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current knife edge seal designs are used, then the seal can prevent gas leakage, but the fatigue life is low due to high temperatures and mechanical loads
Solution Approach 1:
The patent changes the geometric parameters of the knife edge seal by introducing an angled design with specific inclusion angles (e.g., 45 degrees) between the radial direction and the seal structure. This angular parameter change optimizes the distribution of thermal and mechanical loads, reducing compressive stress on the seal while maintaining its gas sealing function at high temperatures
Solution Approach 2:
The patent employs asymmetric geometry in the knife edge seal design, where the seal extends at an angle rather than purely radially or axially. This asymmetric configuration creates favorable stress distribution patterns that reduce compressive loads on the seal material, thereby improving fatigue life under high temperature conditions
2Duration of action of stationary object
If the knife edge seal extends radially and axially at an angle, then thermal mechanical fatigue life is enhanced, but the structural complexity increases
Solution Approach 1:
The patent segments the knife edge seal into distinct functional zones: a base portion attached to the rotor, an angled intermediate section, and a sealing tip. This segmentation allows each portion to be optimized for its specific function while simplifying the overall design process and manufacturing considerations despite the angled configuration
Data Source
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AI summary
A seal for a gas turbine engine and a gas turbine engine employing such a seal are disclosed. More specifically, the engine includes a knife edge seal which is better able to withstand the extremely high temperatures and mechanical loads to which gas turbine engine components are increasingly subjected. By moving the knife edge seal to the aft hub and cantilevering its angle off of vertical, thermal and mechanical loads are balanced and thus thermal mechanical fatigue life is improved while low cycle fatigue is maintained.