CMC Seal Arc Segment with Backside Labyrinth Cooling Cavities
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Solution Overview
Problem
Existing gas turbine engine seal systems face challenges in effectively managing thermal stress and leakage around turbine blades due to exposure to high-pressure and temperature exhaust gases, with current cooling methods not adequately addressing the need for precise pressure and flow control within the cooling cavities.
Innovation Solution
A ceramic matrix composite (CMC) seal arc segment with an abradable layer and a carrier featuring a ridge is used to create a labyrinth seal, where the ridge cuts a groove into the abradable layer, partitioning the cooling cavity into sub-cavities, allowing for tailored cooling air flow and pressure management to reduce thermal stress and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cooling cavity is used in the seal system, then the structure is simpler, but the control of cooling air flow and pressure is insufficient
Solution Approach 1:
The single cooling cavity is divided into multiple sub-cavities by introducing ridges that extend from the carrier into the abradable layer. This segmentation allows independent control of cooling air flow and pressure in each sub-cavity, enabling precise thermal management of different seal regions while maintaining a relatively simple overall structure.
2Temperature
If cooling air flow is increased to manage thermal stress, then thermal management improves, but leakage around turbine blades increases
Solution Approach 1:
Different sub-cavities are supplied with cooling air at different pressures and flow rates tailored to the specific thermal requirements of each seal region. This localized control allows optimal cooling where needed while minimizing excessive flow that would increase leakage, thereby improving thermal management without proportionally increasing harmful leakage.
3Reliability
If the ridge cuts deeper into the abradable layer, then the labyrinth seal effectiveness improves, but the structural integrity of the abradable layer deteriorates
Solution Approach 1:
The ridges are designed to cut into the abradable layer to a controlled depth that provides sufficient labyrinth seal effectiveness for reliable operation, without cutting so deep as to compromise the structural integrity of the abradable layer. This partial action achieves the necessary sealing performance while maintaining adequate strength.
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 enhances thermal management and reduces leakage by compartmentalizing the cooling cavity, enabling precise control of cooling air flow and pressure, thereby improving the structural integrity and efficiency of the gas turbine engine's seal system.
Implementation Method 1
sliding the CMC seal arc segment relative to the carrier such that during the sliding the ridge cuts a groove into the abradable layer
Implementation Method 2
The ridge remains disposed in the groove to thereby provide a labyrinth seal that partitions the cooling cavity between the carrier and the CMC seal arc segment into sub-cavities
Data Source
AI summary
A method includes providing a ceramic matrix composite (CMC) seal arc segment that has radially inner and outer sides, attaching an abradable layer on the radially outer side of the CMC seal arc segment, providing a carrier to support the CMC seal arc segment, the carrier including a ridge, and sliding the CMC seal arc segment relative to the carrier such that during the sliding the ridge cuts a groove into the abradable layer, the ridge remaining disposed in the groove to thereby provide a labyrinth seal that partitions the cooling cavity between the carrier and the CMC seal arc segment into sub-cavities.