Cooled Attachment Sleeve for CMC Rotor Blade
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Solution Overview
Problem
Ceramic matrix composite (CMC) rotor blades in gas turbine engines face issues with significant radial tension and thermal stresses due to their long neck regions and high orthotropy, which can lead to structural integrity problems and excessive interlaminar stresses, while aggressive cooling may cause unacceptable thermal gradients.
Innovation Solution
A metal alloy sleeve is additively manufactured with multiple passages and circumferential extensions that overlap to surround the CMC rotor blade root, providing a cooling mechanism that reduces heat transfer to the rotor disk and minimizes thermal stresses by shielding the rim and disk lug from high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a relatively long neck region is used to separate the hot airfoil section from the cooler root section, then heat conduction from the airfoil to the root is improved, but radial tension and bending moments on the rotating rotor blade increase significantly
Solution Approach 1:
A metal sleeve is introduced as an intermediary component between the CMC rotor blade root and the nickel-based super alloy rotor disk. The sleeve acts as a thermal and mechanical mediator, allowing heat conduction while reducing the radial tension and bending moments on the rotor blade through its structural design and material properties.
2Temperature
If aggressive cooling is applied to the root section to reduce temperatures, then the temperature of the root section is lowered, but thermal gradients and thermal stresses in the CMC rotor blade increase
Solution Approach 1:
The metal sleeve serves as a thermal intermediary that moderates heat transfer between the hot airfoil section and the cooler root section. By controlling the thermal gradient through the sleeve's conduction properties, the system achieves root section cooling while minimizing excessive thermal stresses in the CMC blade.
Solution Approach 2:
The invention changes the thermal parameter distribution by introducing a sleeve with specific thermal conductivity properties. This modifies the heat conduction path and thermal gradient profile, allowing the root section to operate at lower temperatures without creating unacceptable thermal stresses in the CMC material.
3Temperature
If a relatively long neck region is used to conduct heat into the root section, then heat conduction is improved, but bending moments may pry apart the plies in the neck region perpendicular to the radial loading direction
Solution Approach 1:
The metal sleeve acts as a structural intermediary that supports the CMC rotor blade root. It provides mechanical reinforcement that prevents bending moments from prying apart the plies in the neck region, while simultaneously facilitating controlled heat conduction from the airfoil section to the root section.
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 solution effectively reduces thermal gradients and stresses in CMC rotor blades, allowing them to operate at higher temperatures with reduced cooling air usage, maintaining the rotor disk within acceptable temperature ranges and minimizing structural risks.
Implementation Method 1
the relatively high conductivity of the CMC materials, which conducts heat from the airfoil section, into the neck section, then into the root section
Implementation Method 2
Gas path components, such as turbine blades manufactured of nickel-based super alloys that operate in the high temperatures encountered by aerospace and gas turbine engines, typically include airfoil cooling that may be accomplished by external film cooling, internal air impingement, and forced convection
Data Source
AI summary
A rotor disk assembly for a gas turbine engine includes a rotor disk with a multiple of blade slots, the rotor disk defined about an axis; a sleeve received within each of the multiple of blade slots; and a ceramic matrix composite rotor blade received within each of the multiple of sleeves.