Turbomachine Blade Platform Insert for Friction Vibration Damping
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Solution Overview
Problem
Existing turbomachine blade assemblies using torsion prestress to damp vibrations face issues with varying contact stress due to blade rotation and material limitations, particularly with CMC materials, leading to excessive static stresses.
Innovation Solution
A bladed turbomachine assembly with an insert arranged between platforms, featuring circumferentially oriented bearing faces and grooves, allowing friction-based vibration damping without prestress, accommodating dimensional variations through complementary contact faces and radial/circumferential play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torsion prestress is applied to blades during mounting, then vibration damping is improved, but contact stress varies and material strength is compromised
Solution Approach 1:
The blade assembly is segmented into multiple blades with individual platforms, allowing independent vibration damping mechanisms for each blade without requiring global prestress of the entire assembly
Solution Approach 2:
An intermediary element (insert or damping mechanism) is introduced between the blade platforms to provide friction-based vibration damping without requiring the blade material itself to承受 high prestress stresses
2Reliability
If specific platform shapes are used for interlocking, then vibration damping is improved, but adaptability to position variations is reduced
Solution Approach 1:
The platform geometry is designed with dynamic characteristics, allowing the platforms to adapt their relative positioning while maintaining contact for vibration damping, rather than being locked into a fixed interlocking configuration
Solution Approach 2:
The platform shapes and orientations are designed to allow changes in relative position parameters while maintaining sufficient contact area for friction-based vibration damping, providing flexibility in assembly configuration
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
Effectively dampens vibrations by friction, compensating for blade expansion and material limitations, maintaining contact and reducing amplitude without inducing excessive static stresses.
Implementation Method 1
the prestress mentioned above, associated with a specific mounting, produces friction stresses allowing to reduce the amplitude of the vibrations
Data Source
AI summary
A bladed turbomachine assembly including at least two adjacent blades, each blade including a radial aerofoil and a platform located at a free radial end of the aerofoil, the platform of each blade of the bladed assembly being located circumferentially facing a platform of the other circumferentially adjacent blade of the bladed assembly, the bladed assembly including an insert arranged circumferentially between the platforms and which cooperates with the platforms, each platform including a circumferential bearing face against which a circumferential end of the insert is in contact, and the direction of the contact between each circumferential bearing face and the insert being oriented circumferentially with respect to the main axis (A).