Partitioned Pocket Damper Seals for Turbomachine Drum Vibration
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Solution Overview
Problem
Gas turbine engines experience excessive vibrations due to fundamental modes such as cantilevered drum mode, diametral mode, and out-of-phase crunch mode, which can lead to damage and reduced efficiency, necessitating effective damping solutions.
Innovation Solution
The implementation of partitioned pocket damper seals with annular bodies featuring inner and outer circumferential surfaces, defining cavities and plenums, and partitions to provide radial damping between rotor blades and rotatable annular drum rotors, effectively restricting airflow and reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional labyrinth seals are used, then the structure is simple, but the damping effectiveness is insufficient to prevent excessive vibrations
Solution Approach 1:
The seal structure is segmented into multiple functional zones including inlet regions, cavities, partitions, and outlet regions. The partitions divide the seal into multiple cells or chambers, creating a complex flow path that enhances damping effectiveness while maintaining a manageable structural complexity.
Solution Approach 2:
The damper seal integrates multiple functional elements within a single annular structure, nesting cavities, partitions, and flow paths within each other. This allows the complex damping function to be achieved within a compact radial envelope, improving reliability without excessive complexity.
2Object-affected harmful factors
If damping structures are added to reduce vibrations, then vibration reduction is achieved, but the radial space requirements increase
Solution Approach 1:
The damper seal utilizes the axial dimension extensively, creating long, winding flow paths through the seal structure that extend in the axial direction rather than requiring increased radial clearance. This allows effective damping to be achieved within compact radial dimensions by exploiting the third dimension.
Solution Approach 2:
The seal uses pneumatic principles to create damping through controlled airflow resistance. The cavities and partitions generate pressure drops and flow resistance that dissipate vibrational energy, achieving vibration reduction through fluid dynamic effects rather than mechanical mass, thus minimizing radial space requirements.
3Reliability
If airflow is restricted to increase damping, then vibration damping improves, but the pressure drop across the seal increases
Solution Approach 1:
The seal structure implements local variations in flow resistance through strategically placed partitions and cavities. Different regions of the seal have different damping characteristics, with higher resistance in regions where vibration damping is most needed and lower resistance where pressure recovery is prioritized, optimizing the balance between damping performance and pressure drop.
Solution Approach 2:
The damper seal creates dynamic flow patterns that change with operating conditions and vibration amplitudes. The nonlinear flow resistance characteristics allow the seal to provide adaptive damping, where the pressure drop and damping force adjust automatically based on the instantaneous flow conditions and vibrational inputs.
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 seals significantly enhance damping benefits over conventional labyrinth seals, effectively reducing vibrations and improving operational efficiency while maintaining compact design requirements.
Implementation Method 1
a damper seal configured to restrict the airflow in certain directions to increase damping, thereby reducing vibrations of the rotating drums
Data Source
AI summary
A damper seal for a turbomachine includes an annular body having an inner circumferential surface and an outer circumferential surface separated by a thickness. As such, the inner circumferential surface may define a plurality of cavities arranged into a plurality of circumferential rows and at least one partition positioned between at least two of the plurality of cavities. In addition, the inner circumferential surface may further define at least one plenum arranged between two of the plurality of circumferential rows.