CMC Turbine Blade Internal Support and Cooling
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Solution Overview
Problem
Ceramic matrix composite (CMC) turbine blades face issues with low thermal coefficient of expansion, low strain to failure, and poor wear characteristics, leading to material loss and reduced interlock load due to chipping, cracking, and impact damage, as well as inefficiencies in cooling other components within the turbine engine.
Innovation Solution
The design incorporates an internal structural support with a lighter-weight ceramic matrix composite aerodynamic fairing and a metallic support cap, featuring an internal cooling airflow path that extends radially through the support, allowing cooling air to reach the blade tip shroud and reduce material loss, while using seal teeth to minimize leakage and enhance mechanical stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If CMC materials are used for turbine blades to achieve high temperature capability and light-weight, then weight is reduced and temperature resistance is improved, but wear resistance deteriorates and susceptibility to chipping and cracking increases
Solution Approach 1:
The patent uses ceramic matrix composite (CMC) materials for the turbine blade, which combine ceramic fibers in a matrix to create a composite structure that maintains the inherent advantages of CMC (light weight, high temperature capability) while improving damage tolerance through the composite architecture. The composite structure allows for crack propagation without immediate failure, addressing the brittleness issue.
2Temperature
If CMC materials are used for turbine blades to achieve high temperature capability, then temperature resistance is improved, but wear characteristics deteriorate leading to material loss
Solution Approach 1:
The patent applies a protective coating to the CMC turbine blade surface before operation. This coating serves as a sacrificial layer that protects the underlying CMC material from direct exposure to harsh environmental conditions, including thermal oxidation and particle erosion, thereby reducing material loss while maintaining the high temperature capability of the CMC substrate.
3Temperature
If bleed air is used to cool turbine rotor blades through cooling passages, then blade cooling is achieved, but the bleed air cannot be used to cool other components within the turbine
Solution Approach 1:
The patent designs the cooling system so that bleed air cooling passages are provided not only in the turbine rotor blades but also in other turbine components such as the turbine stator vanes and tip shrouds. This multi-functional cooling approach allows the same bleed air source to cool multiple components simultaneously, increasing the versatility and efficiency of the cooling system.
4Weight of moving object
If CMC on CMC contact is used at interlock faces of blade tip shrouds to reduce weight, then weight is reduced, but wear characteristics deteriorate leading to loss of interlock load
Solution Approach 1:
The patent applies different material properties to different regions of the blade tip shroud. The main body of the shroud uses CMC material for weight reduction, while the interlock contact surfaces are either protected by specialized coatings or designed with geometry that minimizes direct CMC-on-CMC contact. This localized differentiation maintains the lightweight advantage while protecting the critical interlock interfaces from wear-induced strength loss.
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 configuration reduces material loss, improves wear resistance, and provides internal cooling to the CMC turbine blades, enhancing the durability and performance of the engine by maintaining interlock load and reducing tip leakage.
Implementation Method 1
an internal cooling airflow path that extends radially through the support
Implementation Method 2
The seal teeth typically are in the form of a honeycomb covered stator shroud
Data Source
AI summary
A gas turbine engine turbine blade includes internal structural support radially supporting aerodynamic fairing.Strut radially extends away from root of support. Fairing includes hollow fairing airfoil surrounding strut and extending from fairing platform to blade tip shroud at tip of the fairing airfoil. A support cap attached to radially outer end of strut outwardly restrains fairing. Seal teeth may extend outwardly from the support cap. Internal cooling air flow path may extend radially through support. Fairing may be made from material lighter in weight than the support. Fairing material may be ceramic matrix composite and support material may be metallic. Blades may be mounted in rim of disk by roots disposed in slots through rim. Annular plate mounted to, upstream of, and proximate web of disk defines in part cooling airflow path to slot.