Cantilevered CMC Turbine Rotor Deflection Reduction
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Solution Overview
Problem
Gas turbine engines face deflections during operation due to various loads, which can lead to structural issues and inefficiencies, particularly in the turbine rotors supported by bearing assemblies.
Innovation Solution
The design incorporates a turbine section with a second turbine rotor having a disk assembly made of ceramic matrix composite (CMC) materials, supported by an aft bearing assembly, and a mid-turbine frame that reduces the metallic content and includes a geared architecture with blade outer air seals to minimize deflections and optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional metallic materials are used for the turbine rotor disk assembly, then structural strength and reliability are maintained, but weight and spinning mass increase
Solution Approach 1:
The patent applies composite materials by replacing traditional metallic disk assemblies with ceramic matrix composite (CMC) materials. The CMC disk assembly maintains structural strength and heat resistance while significantly reducing weight. The composite structure consists of ceramic matrix material reinforced with ceramic fibers, providing high strength-to-weight ratio suitable for turbine rotor applications.
2Device complexity
If the aft portion of the turbine shaft is cantilevered from the bearing assembly, then device complexity is reduced, but deflections increase during operation
Solution Approach 1:
The patent changes the material parameter of the turbine shaft by using CMC materials instead of traditional metallic materials. This parameter change allows the shaft to have lower density and different mechanical properties that reduce deflections during operation. The CMC material provides high strength-to-weight ratio and resistance to thermal and mechanical stresses, enabling the cantilevered configuration to maintain stability.
3Weight of moving object
If CMC materials are used for turbine blades, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent uses CMC materials for turbine blades to achieve weight reduction while maintaining structural integrity. The composite material consists of ceramic matrix with ceramic fiber reinforcement, providing high strength and heat resistance. The manufacturing process involves forming the composite material into blade shapes and then sintering or curing the material to achieve final mechanical properties.
Data Source
AI summary
A turbine section for a gas turbine engine according to an example of the present disclosure includes, among other things, a first turbine rotor coupled to a first turbine shaft. The first turbine shaft is rotatable about a longitudinal axis. A second turbine rotor is coupled to a second turbine shaft. The second turbine shaft is rotatable about the longitudinal axis, and the second turbine rotor is axially aft of the first turbine rotor relative to the longitudinal axis. An aft bearing assembly rotatably supports the second turbine shaft. The second turbine rotor includes a disk assembly that carries at least one row of turbine blades. The disk assembly is mechanically attached to the second turbine shaft at an attachment point. The attachment point is axially aft of the aft bearing assembly such that an aft portion of the second turbine shaft is cantilevered from the aft bearing system with respect to the longitudinal axis. The disk assembly includes a metallic material. Each of the turbine blades comprises a ceramic matrix composite (CMC) material.