Fluidic Rotor Blade Damper for Shroud-Free Vibration Control
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Solution Overview
Problem
Conventional vibration damping methods for turbomachine rotor blades, such as shrouds, increase weight and cost while causing aero performance losses and high aeroelastic flutter instability, and are ineffective for aft-stage blades with short shanks.
Innovation Solution
A vibrational dampening element that adjusts or eliminates shrouds by using a fluidic chamber with a mass suspended within, utilizing viscous damping forces to reduce oscillations without obstructing airflow, tuned to specific frequency ranges of the rotor blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shrouds are used for vibration damping, then vibration damping is provided, but weight increases and aero performance losses occur
Solution Approach 1:
The patent extracts the damping function from the traditional shroud structure and implements it through a separate tuned mass damper system. The damper consists of a mass suspended by springs within a cavity in the blade, allowing vibration damping without the need for conventional shrouds that increase weight and cause aero performance losses.
Solution Approach 2:
The patent introduces springs as an intermediary element between the blade structure and the damping mass. These springs serve as the coupling mechanism that allows the mass to absorb vibrations while maintaining a lightweight structure, replacing the direct contact shroud approach.
2Reliability
If shrouds are used for vibration damping, then vibration damping is provided, but aero performance losses occur
Solution Approach 1:
The damping function is extracted from the shroud and implemented through a tuned mass damper system embedded within the blade cavity. This eliminates the need for external shrouds that interfere with airflow, thereby maintaining aero performance while providing effective vibration damping.
Solution Approach 2:
The patent moves the damping mechanism from an external shroud structure to an internal cavity-based system. By placing the mass and springs within a cavity in the blade, the solution eliminates the aerodynamic interference caused by external shrouds while maintaining damping effectiveness.
3Reliability
If tip shrouds are used, then vibration damping is provided, but aeroelastic flutter instability is induced
Solution Approach 1:
The patent removes the tip shroud structure entirely and replaces it with an internal tuned mass damper system. This extraction eliminates the source of aeroelastic flutter instability associated with tip shrouds while maintaining vibration damping through the suspended mass and spring mechanism.
4Reliability
If platform dampers are used, then vibration damping is provided, but they are ineffective for short shank blades
Solution Approach 1:
The patent transitions from external platform dampers requiring blade shank motion to an internal cavity-based tuned mass damper system. This dimensional change allows the damping mechanism to be effective regardless of blade shank length, making it applicable to both long and short shank blades including IGT aft-stage blades.
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 reduces vibration amplitudes of turbomachine rotor blades, enhancing durability and aerodynamic efficiency while minimizing weight and cost, without inducing aero performance losses.
Implementation Method 1
utilizing viscous damping forces to reduce oscillations
Data Source
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AI summary
A vibrational dampening element (300) is attached to a component and configured to adjust the amplitude of oscillations of the component. The vibrational dampening element (300) includes a mass (308). The mass (308) includes a main body (310) and a member (312) extending from the main body (310). A casing (306) that encapsulates the mass (308). A fluidic chamber (309) defined between the mass (308) and the casing (306). A first fluidic portion (318) is disposed between a first side of the mass (308) and the casing (306). The first fluidic portion (318) includes a first accumulator portion (324) directly neighboring the member (312). A second fluidic portion (328) is disposed between a second side of the mass (308) and the casing (306). The second fluidic portion (328) includes a second accumulator portion (334) directly neighboring the member (312). The first accumulator portion (324) is in fluid communication with the second accumulator portion (334). The vibrational dampening element (300) further includes a primary passage (362) that extends between the first fluidic portion (318) and the second fluidic portion (328).