Non-integral Platform Segments for Turbine Blade Vibration Damping
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Solution Overview
Problem
The use of ceramic matrix composite (CMC) materials in turbine blades requires complex design modifications, which can negate the benefits of using these materials, and existing turbine blade designs with integral airfoils and platforms face challenges in simplifying geometry and reducing blade attachment pull.
Innovation Solution
A rotor design featuring non-integral, circumferentially movable platform segments with hooks that interlock with attachment members secured to the rotor hub, allowing for independent mounting and replacement of ceramic blades and platform segments, which simplifies the design and reduces attachment pull by allowing circumferential movement to dampen vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CMC material is used in turbine blades, then material strength and temperature resistance are improved, but design complexity increases
Solution Approach 1:
The blade is divided into separate modular components: the CMC airfoil section and the metal platform section. This segmentation allows each component to be optimized for its specific material properties while simplifying the overall design process. The airfoil can be designed as a simple CMC component without complex integration requirements for the platform attachment.
Solution Approach 2:
The platform is extracted from the integral blade structure and made as a separate removable component. This extraction eliminates the need for complex design modifications required for integral CMC platforms, allowing the CMC airfoil to be used in its optimal form while the platform attachment is handled separately through standardized interfaces.
2Strength
If integral airfoil and platform design is used, then structural strength is improved, but geometry simplification and attachment pull reduction are worsened
Solution Approach 1:
The blade assembly is segmented into the airfoil component and the platform component that can be independently designed and assembled. This segmentation simplifies the geometry of each individual component while maintaining structural strength through proper interface design with attachment members.
Solution Approach 2:
The attachment connection is moved from a radial dimension to an axial dimension, allowing the platform to attach to the airfoil through axial loading on the attachment members rather than radial forces, thereby reducing attachment pull and simplifying the overall geometry.
3Loss of energy
If non-integral platform segments with circumferential movement freedom are used, then vibration damping is improved, but structural rigidity is reduced
Solution Approach 1:
The platform segments are designed with controlled circumferential movement capability relative to the blades, transforming the rigid static connection into a dynamic semi-rigid connection. This allows the system to adapt to vibrational loads by permitting limited relative motion that dissipates energy while maintaining sufficient structural rigidity for normal operation.
Solution Approach 2:
The potential harmful effect of platform-blade relative motion is converted into a beneficial vibration damping mechanism. The circumferential movement freedom allows frictional energy absorption during relative motion, transforming what could be structural instability into an active vibration control feature.
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 design simplifies the geometry of ceramic matrix, fiber-reinforced turbine blades, reduces attachment pull, and allows for independent repair and replacement of components, while effectively damping vibrations through frictional energy absorption.
Implementation Method 1
allows circumferential movement to dampen vibrations
Data Source
AI summary
A rotor includes a rotor hub, a plurality of blades mounted in a circumferentially-spaced arrangement on the rotor hub and a plurality of platform segments circumferentially arranged, respectively, between neighboring ones of the blades. The platform segments include core gas-path defining surfaces and are mounted with a freedom to circumferentially move relative to the neighboring ones of the blades.