Gas Turbine Sheet Metal Casing Damping at Peak Vibration Points
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engine inter compressor casings experience vibration-related issues due to modal interference within the engine speed range, leading to potential structural excitation and displacement concerns.
Innovation Solution
A sheet metal casing design with strategically placed dampers, where one end is fixed to the casing and the other end has an interference fit that prevents relaxation, providing a bias force to dampen vibrations at peak displacement points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inter compressor casing is formed of sheet metal welded to form a full hoop structure, then the structural integrity and manufacturing feasibility are improved, but vibration-related issues and modal interference occur within the engine speed range
Solution Approach 1:
The patent applies local quality by placing dampers at specific locations on the casing where vibration peaks occur. Rather than treating the entire casing uniformly, the solution targets specific problem areas (peak displacement points) with localized damping treatment. This allows the majority of the casing to maintain its simple sheet metal construction while addressing vibration issues only where needed.
Solution Approach 2:
The damper acts as an intermediary element between the vibrating casing and the vibration energy. It is fixed to the casing at one end while having its second end constrained by the casing wall, creating an intermediate mechanism that absorbs and dissipates vibration energy without requiring fundamental changes to the casing structure itself.
2Reliability
If dampers are placed at peak displacement points to reduce vibration, then vibration-induced displacement is reduced, but the device complexity increases
Solution Approach 1:
The damper design maintains simplicity through local quality by concentrating the vibration control function in small, discrete elements placed only at peak displacement points. The dampers are relatively simple components compared to the entire casing structure, and their localized placement means most of the casing remains unchanged and simple.
Solution Approach 2:
The interference fit design allows the damper to be self-installing and self-adjusting. The second end of the damper is constrained by the casing wall geometry itself, eliminating the need for additional fastening mechanisms or complex mounting arrangements. The structure serves its own function of constraining the damper.
3Reliability
If the second end of the damper is not fixed to the casing but provides an interference fit, then the damper can provide bias force to dampen vibrations, but the manufacturing precision requirements increase
Solution Approach 1:
The design extracts the vibration damping function from the main casing structure by using a separate damper component. The interference fit feature is extracted as a specific geometric constraint that provides the necessary constraint without requiring complex fastening systems. This separation allows the damping function to be added without fundamentally altering the casing design.
Solution Approach 2:
The interference fit design changes the constraint parameter from fully fixed (rigid connection) to constrained but allowable movement (interference fit). This parameter change enables the damper to provide bias force and accommodate thermal expansion while still effectively damping vibrations, balancing manufacturing feasibility with functional performance.
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 solution effectively reduces vibration-induced displacement at critical points within the engine speed range, enhancing the structural stability and operational reliability of the gas turbine engine.
Implementation Method 1
A damper is placed on a wall of the casing at the at least one potential peak displacement point. The damper has one end fixed to the casing, and a second end not fixed to the casing and the second end provides an interference fit such that the second end cannot move to a relaxed position of the second end due to the wall of the casing.
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
A gas turbine engine (20) includes a compressor section (24), a combustor (26) and a turbine section (28). At least one casing (202) surrounds at least one of the compressor and turbine sections. The at least one casing (202) is formed of sheet metal. The at least one casing has at least one potential peak displacement point (210) due to vibration across a speed range of the one of the compressor and turbine sections. A damper (220) is placed on the casing at the at least one potential peak displacement point (210). The damper (220) has one end fixed to the casing (202), and a second end (224) not fixed to the casing, and the second end (224) provides an interference fit such that the second end (224) is biased against the outer wall of the casing and cannot move to a relaxed position of the second end due to the wall of the casing (202).