Pin-Based Attachment for Turbine Blade Roots
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Solution Overview
Problem
Existing attachment systems for composite material turbine blades to rotor disks face challenges in mechanical strength due to force direction mismatch and rapid deterioration from fatigue and oxidation, particularly with bulb-shaped roots which are complex and costly to fabricate.
Innovation Solution
A pin-based attachment system where pins pass through blade roots in a direction perpendicular to the fiber layers, allowing forces to act within the planes of the fiber texture for enhanced mechanical strength, and enabling thermal expansion compensation by pinning multiple blades, with options for pin shape, material, and reinforcement to reduce costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bulb-shaped blade roots are used with co-operating slots in the rotor disk, then the blades can be attached to the rotor disk, but the retaining forces cause compression perpendicular to the fiber texture layers leading to rapid deterioration from fatigue and oxidation
Solution Approach 1:
The patent inverts the traditional attachment approach by using a pin that passes through the blade root perpendicular to the fiber layers rather than relying on the fiber layers to directly resist the retaining forces. This inversion allows the pin to bear the compression loads while the fiber layers maintain their optimal orientation for tensile strength, thereby resolving the contradiction between durability and mechanical strength.
Solution Approach 2:
The pin acts as an intermediary element between the blade root and the rotor disk. It mediates the force transmission by carrying the retaining forces through its structure, preventing these forces from acting directly on the fiber texture layers of the composite material. This intermediary solution protects the blade root from compression perpendicular to the fiber layers while maintaining strong attachment.
2Reliability
If bulb-shaped roots are used for blade attachment, then the blades can be secured to the rotor disk, but the fabrication becomes complex and expensive
Solution Approach 1:
The attachment system is segmented into distinct functional elements: a simplified blade root with a hole and a separate pin component. This segmentation allows the blade root to be manufactured as a simple slab shape without complex bulbous formations, while the pin provides the necessary attachment function. The segmentation thus reduces fabrication complexity while maintaining attachment security.
Solution Approach 2:
The patent changes the geometric parameters of the blade root from a complex bulb-shaped form to a simple slab shape with a hole. This parameter change simplifies the manufacturing process and reduces costs, while the attachment security is maintained through the pin mechanism that provides the mechanical connection to the rotor disk.
3Strength
If pins pass through blade roots perpendicular to fiber layers, then forces act within the planes of fiber texture enhancing mechanical strength, but the pin must withstand significant retaining forces in a limited space
Solution Approach 1:
The pin is made of metal material that forms a composite attachment system with the composite material blade root. This composite solution allows the pin to withstand the significant retaining forces through its high strength-to-weight ratio and ductility, while the blade root maintains its optimal fiber orientation for enhanced mechanical strength in the plane of the layers.
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 pin-based system enhances mechanical strength and durability of composite material blade roots, reduces production costs, and allows for thermal expansion compensation, providing a robust and cost-effective attachment solution that mitigates the drawbacks of existing systems.
Implementation Method 1
the retaining forces exerted by the rotor disk on the root of a blade act essentially within the planes of the layers of fiber texture making up the blades (i.e. in the directions of the warp yarns and of the weft yarns making up the various layers of the fiber texture of the composite material blades)
Implementation Method 2
using the same pin to pin two (or more) blades makes it possible to allow the blades (when made of composite material) to move in translation relative to the rotor disk (when it is made of metal) in such a manner as to compensate for thermal expansion differences between those parts
Data Source
AI summary
A device for attaching blades to a rotor disk of a turbine engine is provided. The device includes: a rotor disk provided at its outer periphery with a plurality of slots, each slot being formed between two adjacent disk teeth and extending axially between front and rear faces of the disk; a plurality of blades, each having a respective root mounted in a slot of the disk; and at least one pin mounted in the rotor disk to pass through the roots of at least two adjacent blades and extending between the front and rear faces of the rotor disk so as to attach the blades to the rotor disk.