Dynamic Blade Outer Air Seal Radial Translation
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Solution Overview
Problem
Conventional blade outer air seals (BOAS) in gas turbine engines inhibit radial motion during aircraft maneuvers, leading to reduced cooling air passage and potential contact with blade tips due to thermal and pressure-induced deflections, which limits the effectiveness of cooling air compartment sealing.
Innovation Solution
A seal design comprising a first portion with channels and a second portion with projections, allowing for radial translation of the BOAS, coupled with a low friction coating such as Titanium Nitride or solid lubricants, to accommodate thermal expansion and contraction while maintaining effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seals are used to prevent cooling air leakage between BOAS sections, then sealing effectiveness is improved, but radial motion of the BOAS is inhibited
Solution Approach 1:
The seal transitions from a static conventional design to a dynamic design where the seal elements can move radially. The seal comprises a body with seal elements that are capable of radial displacement to accommodate BOAS expansion and contraction during aircraft maneuvers, while still maintaining sealing functionality through controlled contact between seal surfaces.
Solution Approach 2:
The seal is divided into a body and separate seal elements that can move independently. The seal elements are positioned within the body and can slide radially to accommodate thermal expansion and contraction of the BOAS, allowing the seal to maintain both sealing effectiveness and adaptability to radial motion.
2Reliability
If the BOAS is constrained to prevent cooling air leakage, then sealing performance is improved, but thermal expansion and contraction are restricted
Solution Approach 1:
The seal incorporates dynamic elements that can move radially in response to thermal expansion and contraction of the BOAS. The seal elements are designed to slide within the seal body, accommodating dimensional changes in the BOAS while maintaining the sealed environment for cooling air compartments.
Solution Approach 2:
The seal design allows for parameter changes in the radial direction through movable seal elements. As the BOAS expands or contracts thermally, the seal elements adjust their radial position accordingly, maintaining sealing effectiveness across varying thermal conditions without restricting the BOAS dimensional changes.
3Reliability
If friction between seal surfaces is increased to improve sealing contact, then sealing effectiveness is improved, but radial motion is hindered
Solution Approach 1:
The seal incorporates a compliant coating on the seal elements that provides both sealing contact and low friction. This flexible layer allows the seal elements to maintain contact with the sealing surface while reducing friction during radial motion, enabling smooth translation during aircraft maneuvers.
Solution Approach 2:
The seal elements are constructed with composite materials or coatings that combine sealing properties with low friction characteristics. This composite structure allows the seal to maintain effective sealing contact while enabling smooth radial motion through the compliant, low-friction surface layer.
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
Enables controlled radial motion of the BOAS, reducing cooling air leakage and maintaining proper clearance between blade tips and the seal, ensuring efficient cooling air distribution and operational stability during aircraft maneuvers.
Implementation Method 1
the first portion and/or the second portion may be coated with a low friction substance
Implementation Method 2
The thermal and pressure induced deflections of individual components may require that some seals perform with substantial relative motion between sealing surfaces
Implementation Method 3
the first projection slidably couples to the first channel and the second projection slidably couples to the second channel
Data Source
AI summary
The present disclosure relates to a first seal for an aircraft blade outer air seal (“BOAS”) comprising a first portion comprising a first channel and a second channel, and a second portion comprising a first projection and a second projection, wherein the first projection slidably couples to the first channel and the second projection slidably couples to the second channel. The first portion and/or the second portion may be coated with a low friction substance. The first portion may be coupled to a vane support and/or a BOAS, and the second portion may be coupled to a first OAS support. The first seal may enable a radial translation of the BOAS in response to an aircraft maneuver.