Variable Thickness Damper Seal for Gas Turbine Blade
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Solution Overview
Problem
Seal dampers in gas turbine engines experience unintended bulk tangential movement due to dynamic forces, leading to inefficiencies in vibration damping, as they lack sufficient restraint devices, which increases weight and reduces stiffness.
Innovation Solution
A damper seal with a variable thickness, featuring a taper or stepped design along its minor axis, is used to restrain movement by offsetting normal forces, allowing it to lock on the heavier side and slip on the lighter side, thereby enhancing damping efficiency without additional weight-increasing restraint devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If restraint devices are added to prevent damper movement, then damper stability improves, but weight increases and stiffness decreases
Solution Approach 1:
The damper seal employs asymmetric thickness distribution across its width, with a first thickness at the leading edge and a second thickness at the trailing edge. This asymmetric geometry creates unequal normal forces on opposite sides of the damper, generating a self-restraining moment that prevents unwanted tangential movement without requiring additional restraint devices, thereby maintaining stability while avoiding weight increase
Solution Approach 2:
The invention applies different thickness properties to different regions of the damper seal. The leading edge portion has a first thickness while the trailing edge portion has a second thickness, creating localized variations in mechanical properties. This local quality differentiation enables the damper to self-restrain through uneven force distribution without adding global weight or reducing overall stiffness
2Stability of the object's composition
If restraint devices are added to prevent damper movement, then damper stability improves, but damper stiffness decreases
Solution Approach 1:
The asymmetric thickness design creates a self-restraining mechanism through unequal normal forces, eliminating the need for external restraint devices that would compromise damper stiffness. The inherent geometric asymmetry provides stability while preserving the structural integrity and stiffness of the damper seal
3Ease of manufacture
If uniform thickness damper seal is used, then manufacturing simplicity is maintained, but unwanted tangential movement occurs
Solution Approach 1:
The asymmetric thickness configuration can be efficiently manufactured using conventional sheet metal forming processes. The taper or stepped profile between the leading and trailing edges can be created in a single forming operation, maintaining manufacturing simplicity while achieving the self-restraining effect that prevents unwanted tangential movement
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 variable thickness damper seal effectively restricts unwanted movement, maintaining damping efficiency while minimizing the need for additional restraint devices, thus optimizing weight and stiffness in high-temperature environments.
Implementation Method 1
the variable thickness of the damper seal may be provided by a taper that extends partially along the minor axis of the damper seal between the opposite peripheral edges of the main body portion
Implementation Method 2
The seal damper is made of a material that is dissimilar from the material of the blades. When the vibratory motions of adjacent blades oppose each other (that is, occur out of phase), the seal damper slides to absorb the energy of vibration.
Implementation Method 3
These dampers are typically made of sheet metal and have been shown to readily conform to the underside of the platform when subjected to centrifugal loads in a high temperature environment due to their lack of stiffness out-of-plane.
Data Source
AI summary
A blade for a gas turbine engine. The blade having: a root; a platform located between the root and the blade, wherein the platform defines a cavity; a damper seal received in the cavity, the damper seal having a main body portion that extends along a major axis of the damper seal between a first end portion and an opposing second end portion of the damper seal, the first end portion and the second end portion each extend towards the root when the damper seal is located in the cavity and wherein the damper seal has a variable thickness along at least a portion of a minor axis of the damper seal that extends between opposite peripheral edges of the main body portion.