Combustor Liner Looped Section for Vibration Damping
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Solution Overview
Problem
The existing liner assemblies in gas turbine engines experience high thermal gradients and vibrations, leading to mechanical stress and potential failure before reaching the designed lifecycle.
Innovation Solution
The proposed liner assembly incorporates a looped section with compliant joints and air cavities that act as acoustic dampers, providing multiple degrees of freedom to absorb vibrations and reduce mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid liner assembly is used in the combustor, then structural strength is maintained, but thermal gradients and vibrations cause mechanical stress leading to premature failure
Solution Approach 1:
The liner assembly incorporates a flexible membrane or diaphragm that can deform elastically in response to thermal gradients and vibrations. This flexible element absorbs mechanical stress through controlled deformation, preventing stress concentration and fatigue failure while maintaining the structural integrity of the overall combustor assembly.
Solution Approach 2:
The patent utilizes materials with specific thermal expansion coefficients and elastic moduli that change with temperature. The liner assembly is designed to accommodate thermal expansion and contraction cycles, allowing the structure to adapt to varying thermal conditions without developing excessive mechanical stress that would lead to premature failure.
2Reliability
If cooling air is directed to the looped section, then vibrations are dampened, but additional cooling air flow requirements increase
Solution Approach 1:
The looped section is specifically designed to resonate at frequencies that counteract the dominant vibration modes in the combustor. By tuning the loop geometry and mass distribution, the structure creates beneficial vibrations that dampen harmful oscillations, reducing mechanical stress on the liner assembly without requiring active control systems or excessive cooling air.
Solution Approach 2:
The looped section structure is designed to utilize the existing thermal and vibrational environment of the combustor to its advantage. The geometry and material properties are selected so that the structure naturally absorbs and dissipates vibration energy through its own thermal and mechanical characteristics, reducing dependence on external cooling air for vibration control.
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 improved liner assembly enhances durability and extends the lifecycle by effectively damping vibrations and mechanical stress, preventing premature failure and maintaining performance throughout the designed operational period.
Implementation Method 1
The looped section includes one or more bends such that the looped section forms a compliant joint and vibrations are dampened through the liner downstream of the looped section
Implementation Method 2
The one or more cavities are sized to dampen acoustic oscillations
Data Source
AI summary
A liner assembly for a combustor. The liner assembly includes a liner defining a combustion chamber of the combustor. The liner includes a looped section at a forward end of the liner. The looped section includes one or more bends such that the looped section forms a compliant joint and vibrations are dampened through the liner downstream of the looped section.