Blade Platform Damper Restraint for Gas Turbine Seal Stability
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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 and a need for additional restraint devices to maximize damper stiffness and minimize weight.
Innovation Solution
A damper restraint system featuring raised features or protrusions on the interior surface of blade platforms that engage tab portions of the damper seal, preventing radial, tangential, and rotational movement, thereby enhancing the damper's stability and reducing unwanted motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seal dampers are made with lack of stiffness out-of-plane to conform to blade platforms, then sealing and damping efficiency is improved, but unintentional bulk tangential movement occurs under dynamic forces
Solution Approach 1:
The damper is segmented into a flexible sealing portion that contacts the blade platform and a restrained portion that engages with restraint features. This segmentation allows the sealing area to conform to the platform while the restrained portion prevents unwanted bulk movement, resolving the contradiction between flexibility for sealing and stability for position control.
Solution Approach 2:
Different regions of the damper are given different mechanical properties: the sealing region is made flexible with low out-of-plane stiffness to conform to the platform surface, while the restraint regions are made stiffer to engage effectively with restraint features. This local differentiation allows simultaneous achievement of sealing efficiency and positional stability.
2Stability of the object's composition
If restraint devices are added to prevent damper movement, then positional stability is improved, but damper weight increases
Solution Approach 1:
The restraint features are merged directly into the blade platform structure as raised features, and the damper is designed with integrated tab portions that engage these features. This merging eliminates the need for separate restraint devices, achieving positional stability without adding significant weight to the moving damper assembly.
Solution Approach 2:
The blade platform structure serves dual purposes: it provides the sealing surface for the damper and simultaneously provides the restraint features through raised features. This self-service approach means the blade structure restrains the damper without requiring additional components, minimizing weight increase while maintaining positional stability.
3Reliability
If multiple restraint devices are used to limit damper movement, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The raised features on the blade platform serve multiple functions: they act as restraint features to prevent damper movement, provide structural support, and maintain positioning during assembly. This multi-functionality achieves operational reliability without increasing device complexity, as the same structural features perform multiple roles.
Solution Approach 2:
The blade platform structure automatically provides restraint functionality through its own geometry (raised features), eliminating the need for separate restraint mechanisms. This self-service approach maintains operational reliability while keeping the system simple, as the blade structure itself performs the restraint function without additional components.
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 damper restraint system effectively limits undesired movement of the damper seal, enhancing its operational efficiency and maintaining structural integrity under centrifugal loads while minimizing the need for additional weight-increasing restraint devices.
Implementation Method 1
provide frictional damping between the blades. The seal damper slides on an underside of the platforms
Implementation Method 2
reduce the vibratory response and provide frictional damping between the blades
Implementation Method 3
conforming to the underside of the platform when subjected to centrifugal loads in a high temperature environment
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A gas turbine engine, having: a disk (70); a plurality of blades (76) secured to the disk, each of the plurality of blades having a platform (74) located between a root portion (78) and an airfoil portion (81) of the blade, wherein the platform of one of the plurality of blades is configured to define a cavity (78) with a platform of an adjacent blade that is secured to the disk; a damper seal (72) located in the cavity and positioned adjacent to a gap (80) defined by edges of the platforms of the blades; and a damper restraint (84) located on an interior surface of each platform, wherein the damper restraint extends into the cavity and is a raised feature configured to contact a peripheral edge portion of a damper seal when it is adjacent to the gap defined by the platforms of the blades.