Gas Turbine Combustor Inner Cap with Integrated Acoustic Dampers
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Solution Overview
Problem
Current gas turbine combustor designs face challenges in effectively damping both high and low frequency acoustic pressure oscillations, which can lead to hardware damage due to combustion instability, and existing additive manufacturing methods require temporary supports for overhang structures, increasing manufacturing time and cost.
Innovation Solution
The design of a gas turbine combustor inner cap with integrated high-frequency and low-frequency dampers that eliminates the need for temporary supports during additive manufacturing, using a direct metal laser melting process to create overhang structures without bending and incorporating purge holes and acoustic ports for efficient damping, while extended resonating tubes are used to target specific frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If additive manufacturing is used to create overhang structures, then manufacturing complexity is reduced, but temporary support structures are required which increase manufacturing time and cost
Solution Approach 1:
The overhang structure is designed to be self-supporting during the additive manufacturing process through geometric optimization. The structure maintains sufficient stiffness and structural integrity during layer-by-layer construction without requiring temporary support elements, thereby eliminating post-processing removal steps and reducing manufacturing time.
2Reliability
If the inner cap design integrates both high-frequency and low-frequency dampers, then acoustic damping performance is improved, but device complexity increases
Solution Approach 1:
Both high-frequency and low-frequency damping functions are integrated into a single unified inner cap structure. The high-frequency damper and low-frequency damper are combined in one component rather than using separate devices, reducing overall system complexity while maintaining comprehensive acoustic damping performance across the full frequency spectrum.
Solution Approach 2:
The inner cap is designed as a multi-functional component that simultaneously serves as a structural element and an acoustic damping device. It incorporates both high-frequency damping capabilities through its geometric features and low-frequency damping capabilities through integrated resonating tubes, eliminating the need for separate damping devices.
3Object-generated harmful factors
If lean premixed combustion is used to reduce NOx emissions, then emission levels are improved, but combustion instability increases causing high dynamic pressure oscillations
Solution Approach 1:
The combustion instability and associated pressure oscillations, which are harmful side effects of lean premixed combustion, are converted into a beneficial damping mechanism. The oscillating pressure waves are channeled into the resonating tubes where they are dissipated through thermal and viscous effects, transforming the harmful acoustic energy into heat and reducing the oscillation amplitude.
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
This solution reduces the weight of the inner cap by 50% and effectively dampens acoustic pressure oscillations across a range of frequencies, preventing hardware failure and simplifying the manufacturing process by eliminating the need for support structures.
Implementation Method 1
the at least one extended resonating tube 83 configured to dampen acoustic pressure oscillations resonating at a target frequency
Implementation Method 2
the at least one damper chamber 97 configured to dampen acoustic pressure oscillations
Implementation Method 3
A laser beam or electron beam is directed onto the bed of metallic powder, locally melting the powder
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A damping system 80 and apparatus are disclosed for dampening acoustic pressure oscillations of a gas flow in a combustor 20 of a gas turbine engine 10 having at least one combustor 20 with a combustor liner 82. A second inner cap 84 portion is disposed on the at least one combustor 20. The second inner cap 84 portion can have a hot surface 85, a cold surface 86, at least one burner opening 87 protruding from the cold surface 86, and at least one neck ring 88 having an internal opening and protruding from the cold surface 86. At least one resonating tube 89 having a resonating tube neck is integrated with and protruding from the at least one neck ring 88. The at least one resonating tube 89 is disposed between adjacent burner openings 87, and is configured such that the radial dimension 95 is less than the axial dimension 92.