Damper Pin Asymmetric Cross-Section Turbine Vibration
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Solution Overview
Problem
Existing damper pins in turbomachines are not effective in independently tuning resonant mode excitation without requiring changes to the turbine blade design, leading to potential costly tooling rework if they do not perform as expected during engine testing.
Innovation Solution
A damper pin with a discontinuous cross-sectional shape, featuring an elongated body with a center portion and end portions that define a generally arcuate top surface, and a diverging or converging bottom portion, designed to contact the groove between turbine blades, allowing for independent mode tuning without altering the existing blade design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional round or flat damper pins are used, then the damper structure is simple and easy to manufacture, but the damper effectiveness is insufficient and cannot independently tune resonant mode excitation
Solution Approach 1:
The damper pin employs an asymmetric discontinuous cross-sectional shape with a semi-circular first portion, a rectangular second portion, and a circular third portion arranged in sequence along the longitudinal axis. This asymmetric geometry creates distinct inertial properties and natural frequencies that enable independent mode tuning without requiring changes to the turbine blade design, thereby improving damper effectiveness while maintaining manufacturing feasibility.
2Reliability
If complex wedge shaped dampers are used to improve damping performance, then the damping effectiveness may be improved, but the manufacturing complexity increases and tooling rework becomes necessary if performance is not met
Solution Approach 1:
The damper pin cross-section is segmented into three distinct portions: a semi-circular first portion, a rectangular second portion, and a circular third portion. This segmentation allows each portion to contribute differently to the damping characteristics, enabling fine-tuning of resonant mode excitation. The segmented design achieves complex damping performance while remaining manufacturable through standard machining processes, avoiding the need for costly tooling rework.
3Ease of manufacture
If the damper pocket geometry is locked in by hard tooling before testing, then the manufacturing process is simplified, but any damper performance issues require expensive tooling rework
Solution Approach 1:
The damper pin incorporates a dynamic adjustment mechanism where the discontinuous cross-sectional geometry with its three distinct portions allows for natural frequency tuning. The varying cross-sectional areas and mass distribution along the longitudinal axis enable the damper to be tuned to specific resonant modes. This dynamic design capability is achieved within a fixed tooling setup, as the tuning is accomplished through the inherent geometric properties of the damper pin itself rather than requiring adjustable pocket geometries in the turbine 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
The damper pin effectively dissipates vibrational energy and reduces vibration amplitude, providing improved damping performance and allowing for natural frequency tuning without the need for design changes, thus minimizing costly rework.
Implementation Method 1
vibration dampers are typically provided below and/or between the platforms to frictionally dissipate vibratory energy and reduce the corresponding amplitude of vibration during operation
Data Source
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AI summary
A damper pin 100 for damping adjacent turbine blades 28 coupled to a rotor shaft includes an elongated body 102 having a center portion 104 that is disposed between a first end portion 106 and a second end portion 108. The first end portion 106, center portion 104 and second end portion 108 at least partially define a generally arcuate top portion 110 of the elongated body 102. At least a portion of the top portion (110) may be configured to contact with a groove 48 that is defined between the adjacent turbine blades 28. The first end portion 106 and the second end portion 108 have substantially semi-cylindrical cross sectional shapes and the center portion 104 has a cylindrical cross sectional shape. A bottom portion 114 of the elongated body 102 diverges radially outwardly from the first end portion 106 to the center portion 104 and from the second end portion 108 to the center portion 104.