Composite Turbine Blade Damping Device
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Solution Overview
Problem
The challenge in turbomachines is to effectively dampen vibrations in composite material blades, particularly fan blades, due to complex coupling between aerodynamic and elastic characteristics, leading to unpredictable flutter phenomena, which is exacerbated by subsonic flutter and inadequate mechanical damping in current designs.
Innovation Solution
A damping device is integrated into the intrados and extrados walls of composite material blades, comprising a layer of viscoelastic material and a rigid layer with a specific configuration, where the rigid layer has two zones, and the viscoelastic material is interposed between the airfoil and the first zone of the rigid layer, with the second zone attached to the airfoil without viscoelastic material, optimizing damping by maximizing shearing stresses in the peripheral zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damping device is added to the blade, then mechanical damping is improved, but device complexity increases
Solution Approach 1:
The damping device is nested within the blade structure itself, with the viscoelastic layer and rigid layer integrated into the airfoil walls. The rigid layer is positioned between the viscoelastic layer and the external environment, creating a nested configuration that provides damping functionality without adding external components to the blade assembly.
Solution Approach 2:
The damping device utilizes composite material construction, combining a viscoelastic material layer with a rigid layer. This composite structure leverages the complementary properties of both materials - the viscoelastic material provides damping through shear deformation while the rigid layer provides structural support and maintains aerodynamic shape, achieving effective damping without excessive complexity.
2Reliability
If the rigid layer is configured with lobes to maximize shear, then damping effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The rigid layer is configured with lobes or protrusions that extend into the viscoelastic material, creating localized regions of high shear stress. This local quality modification concentrates the damping action in specific areas where the lobe structures maximize shear deformation of the viscoelastic material, thereby improving damping effectiveness without requiring the entire structure to meet high manufacturing precision standards.
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 configuration enhances mechanical damping, particularly for bending and twisting modes, and effectively absorbs impact energy during events like bird strikes, reducing damage and improving harmonic response to aerodynamic excitations, while maintaining aerodynamic properties.
Implementation Method 1
a device for damping the vibrations is incorporated in at least one of the intrados and extrados walls and is formed of at least one layer made of viscoelastic material and a layer made of rigid material
Implementation Method 2
The correct behavior of the damping system is dependent on the dimensions of the material and on good adhesion between the material and the engine part
Implementation Method 3
the rigid layer comprises a first zone and a second zone, the layer made of viscoelastic material being interposed between the airfoil and said first zone of the rigid layer, and said second zone of the rigid layer being attached to the wall of the airfoil without interposition of viscoelastic material
Data Source
AI summary
A blade made of composite material including an airfoil formed of filaments or fibers, optionally woven, impregnated with a heat-curable resin, with an intrados wall and an extrados wall between the leading edge and the trailing edge; and a device for damping the vibrations incorporated in one or other of the intrados and extrados walls is disclosed. The damping device is formed of at least one layer made of viscoelastic material and a layer made of rigid material, these layers being superposed. The layer made of rigid material includes a first zone and a second zone. The layer made of viscoelastic material is interposed between the airfoil and the first zone of the rigid layer, and the second zone of the rigid layer is attached to the wall of the airfoil without interposition of viscoelastic material.