Adjustable Blade Outer Air Seal System for Gas Turbine Tip Clearance Control
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to oversized clearances between turbine blade tips and outer air seals, leading to increased aerodynamic losses, especially as the engine core shrinks and internal components reduce in size, necessitating tighter clearances to optimize performance.
Innovation Solution
A method and system for adjusting blade outer air seal (BOAS) positions using actuators and edge position sensors to maintain predetermined clearances between BOAS and blade tips, with distance measurement devices ensuring precise alignment and minimizing leakage losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clearance between blade tips and outer air seals is increased to avoid rubbing, then reliability is improved, but aerodynamic efficiency deteriorates due to increased tip leakage
Solution Approach 1:
The patent applies dynamics by making the air seal position adjustable rather than fixed. The actuator system allows the air seal to dynamically change its radial position, enabling the clearance to be optimized for different operating conditions - tighter when possible to reduce leakage, and larger when needed to prevent rubbing
Solution Approach 2:
The patent changes the clearance parameter from a fixed design value to a variable parameter that can be adjusted in real-time. By controlling the radial position of the outer air seal through the actuator, the clearance between blade tips and air seal can be modified to optimize both reliability and aerodynamic efficiency under different operating conditions
2Adaptability or versatility
If the engine core diameter is reduced to increase bypass air flow share, then adaptability is improved, but manufacturing precision requirements worsen due to tighter internal clearances
Solution Approach 1:
The adjustable air seal system compensates for the tighter clearances required by the smaller engine core. By dynamically adjusting the air seal position, the system maintains precise clearance control without requiring extremely tight manufacturing tolerances on all internal components
Solution Approach 2:
The system uses parameter changes in the air seal radial position to achieve precise clearance control. This allows the engine to maintain optimal clearances in the reduced-size core while preserving adaptability for bypass air flow optimization
Data Source
AI summary
Controlling BOAS-to-blade-tip clearances by measuring a blade clearance between a first primary BOAS and a blade with a distance measurement device attached to the first primary BOAS, determining if the measured blade clearance of the first primary BOAS is at a value corresponding to a first predetermined blade clearance, measuring a blade clearance of a first secondary BOAS that is circumferentially adjacent the first primary BOAS based on a position of the first primary BOAS when the blade clearance of the first primary BOAS is at the first predetermined blade clearance, determining if the measured blade clearance of the first secondary BOAS is at a value corresponding to the first predetermined blade clearance, and adjusting the position of the first secondary BOAS when the blade clearance of the first secondary BOAS is not at the first predetermined blade clearance with an actuator operably connected to the first secondary BOAS.