Ceramic Matrix Composite Turbine Vane Cooling
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Solution Overview
Problem
The integration of ceramic matrix composite materials in gas turbine engines poses design challenges due to differences in thermal expansion with traditional metallic materials, leading to increased leakage and reduced efficiency as vanes expand and contract, necessitating effective cooling systems to manage temperature and diameter.
Innovation Solution
A turbine case cooling system that includes a vane case cooling unit with a vane case cooling air distributor to manage temperature and diameter of vane supports, using cooling air from a low-pressure source, and optionally conductive metallic strips to actively or passively cool components, controlling circumferential movement of vanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic matrix composite materials are used for vanes, then temperature resistance is improved, but thermal expansion difference with metallic materials causes increased leakage
Solution Approach 1:
The patent applies thermal expansion compensation by actively controlling the temperature of the metallic vane support to counteract differential thermal expansion between ceramic vanes and metallic support. This parameter change approach maintains dimensional compatibility despite different material expansion characteristics, preventing leakage while preserving the high temperature resistance of ceramic materials.
Solution Approach 2:
The patent replaces passive mechanical design with active thermal management. Instead of relying on mechanical clearance adjustments, the system uses active cooling of the metallic support structure to control dimensional changes, substituting a thermal control mechanism for traditional mechanical clearance compensation.
2Loss of energy
If active cooling systems are added to manage thermal expansion, then leakage is reduced, but device complexity increases
Solution Approach 1:
The cooling system is designed to serve multiple functions: it cools the metallic vane support to compensate for thermal expansion differences, manages heat in the turbine assembly, and controls dimensional stability of the vane support. This multi-functionality reduces the need for separate dedicated cooling systems for each purpose.
Solution Approach 2:
The patent combines the cooling of the metallic vane support with the overall turbine cooling strategy, integrating the vane support cooling into the existing cooling air distribution system. This merging approach consolidates multiple cooling functions into a unified system, reducing overall complexity.
3Temperature
If cooling air is diverted to cool the vane support, then thermal expansion is controlled, but engine efficiency decreases due to reduced available cooling air
Solution Approach 1:
The system applies partial cooling to the vane support, using only the amount of cooling air necessary to control thermal expansion and maintain dimensional stability. This partial action approach avoids excessive cooling air consumption while achieving the required thermal expansion control, preserving more cooling air for other critical engine functions.
Solution Approach 2:
The system dynamically adjusts the cooling air flow parameters to the vane support based on operating conditions, optimizing the balance between thermal expansion control and engine efficiency. By varying the cooling air flow rate and temperature, the system maintains effective thermal management while minimizing impact on overall engine performance.
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
The cooling system reduces leakage by managing thermal expansion, improving engine efficiency and specific fuel consumption by controlling the inter-platform gaps between ceramic matrix composite nozzle guide vanes and the metallic turbine casing.
Implementation Method 1
a vane case cooling air distributor configured to discharge cooling air onto the vane support of the turbine case
Implementation Method 2
The strip of metallic material may be actively cooled at a location spaced apart from the vane support of the turbine case
Implementation Method 3
upon contraction and expansion in diameter of the vane support caused by temperatures experienced during use of the turbine assembly
Data Source
AI summary
A turbine assembly according to the present disclosure includes ceramic matrix composite vanes mounted to a metallic case. The turbine assembly includes a turbine case cooling system with a vane case cooling unit configured to manage the temperature and diameter of the metallic case at the location where the ceramic matrix composite vanes are mounted so as to control circumferential movement of the vanes relative to one another during heating and cooling of the turbine assembly when used in a gas turbine engine.