Stiffness Controlled Abradable Seal Cantilever Arm
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Solution Overview
Problem
Existing abradeable seal systems in gas turbine engines lack a controlled stiffness parameter, which affects the operational temperature and durability of the seal interface, leading to potential overheating and metal transfer issues.
Innovation Solution
A stiffness controlled abradeable seal system is introduced, featuring a cantilevered arm with a composite material including MAX phase materials and a solid lubricant, where the stiffness is determined to maintain a desired operational temperature by optimizing the geometry and material selection of the cantilevered arm, and the abradeable seal interface is located between a rotor blade tip and a blade outer air seal with a 25% volume fraction of MAX phase material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the stiffness of the cantilevered arm is increased to maintain seal interface temperature, then the operational temperature stability is improved, but the seal interface pressure increases leading to accelerated wear
Solution Approach 1:
The patent applies parameter changes by systematically varying the stiffness of the cantilevered arm (through material selection and geometric modification) to optimize the balance between maintaining operational temperature stability and controlling seal interface pressure. This involves adjusting physical properties such as moment of inertia, cross-sectional area, and length of the cantilevered arm to achieve desired stiffness values that prevent both overheating and excessive wear.
Solution Approach 2:
The patent employs composite materials in the abradeable seal interface, specifically incorporating MAX phase materials (such as Ti3AlC2) combined with metals like silver, gold, copper, or platinum. These composite materials provide optimized tribological properties that reduce wear while maintaining the ability to form a stable sealing interface, thereby addressing the contradiction between temperature maintenance and wear prevention.
2Loss of substance
If the stiffness of the cantilevered arm is decreased to reduce wear, then the wear rate is reduced, but the operational temperature decreases below optimal sealing conditions
Solution Approach 1:
The patent uses parameter changes by precisely controlling the stiffness parameter of the cantilevered arm within specific ranges that simultaneously achieve acceptable wear rates and maintain optimal sealing temperatures. This involves calculating and selecting appropriate moment of inertia values, cross-sectional areas, and lengths to ensure the stiffness produces sufficient interface pressure for sealing while limiting excessive wear.
Solution Approach 2:
The composite seal materials containing MAX phase materials (e.g., Ti3AlC2) combined with soft metals provide a wear-resistant yet compliant interface that can maintain effective sealing at lower temperatures. The MAX phase materials contribute to reduced wear coefficients while the metal matrix ensures adequate thermal conductivity and sealing capability at reduced interface pressures.
3Reliability
If experimental determination of interface pressure is used, then the seal performance can be optimized, but the design process becomes time-consuming and lacks systematic control
Solution Approach 1:
The patent transforms the empirical trial-and-error approach into a systematic parameter-based design methodology. By establishing direct relationships between cantilevered arm stiffness parameters (material properties, geometric dimensions) and seal performance outcomes (interface pressure, temperature, wear rate), the invention enables predictive design without extensive experimentation. Designers can calculate required stiffness values based on desired operational parameters.
Solution Approach 2:
The patent implements a feedback mechanism where the measured or calculated wear rate and temperature are used to adjust and optimize the cantilevered arm stiffness. This creates a closed-loop design process where performance data feeds back into stiffness optimization, allowing systematic refinement of seal performance without repeated full-scale experimentation.
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 ensures a stable abrasion process, prevents metal transfer and overheating, and maintains the seal interface within a desired temperature range, optimizing seal performance and longevity.
Implementation Method 1
The abradeable seal interface includes a composite of at least one metal combined with a MAX phase material... determining a wear coefficient at the seal interface prior to determining the stiffness and controlling the wear coefficient via a solid lubricant material
Data Source
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AI summary
A stiffness controlled abradeable seal system (80) for a gas turbine engine includes a cantilevered arm (86) that supports one of a rotating seal surface (84) and a static seal surface (82), a stiffness of the cantilevered arm (86) controlled to achieve a desired operational temperature at a seal interface (88).