Combustor Transition With Helmholtz Damper for Thermo Acoustic Decoupling
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Solution Overview
Problem
Gas turbines with can combustors experience dynamic thermo acoustic coupling, leading to strong low-frequency pulsations that negatively affect stability and lifetime, and existing solutions like dampers or fuel staging have drawbacks such as large volume requirements or emission issues.
Innovation Solution
A combustor transition with a wall extension that encloses a Helmholtz-damper resonator volume to decouple thermo acoustic interactions via the turbine inlet, reducing pulsations without the need for fuel staging and minimizing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dampers or resonators are installed in the combustion chamber to mitigate thermo acoustic pulsations, then pulsation mitigation is improved, but device complexity and volume requirements increase
Solution Approach 1:
The patent combines the combustor transition piece with a resonator volume and Helmholtz damper structure into a single integrated component. The transition piece serves dual functions: guiding hot gas flow from the combustor to the turbine and providing thermo acoustic decoupling through the integrated resonator and damper holes, eliminating the need for separate damper installations.
Solution Approach 2:
The combustor transition piece is designed as a multi-functional component that simultaneously performs flow guidance and thermo acoustic decoupling. The side wall extensions create resonator volumes that are fluidly connected to the hot gas flow path through resonator holes, allowing the same structure to handle both aerodynamic and acoustic functions.
2Object-generated harmful factors
If fuel staging is implemented to reduce emissions, then emission performance is improved, but local hot spots and cold spots are created leading to increased NOx and CO emissions
Solution Approach 1:
The patent extracts the thermo acoustic decoupling function from the fuel supply system and implements it through the combustor transition piece structure. By using resonator volumes and Helmholtz dampers in the transition piece, the system achieves pulsation mitigation without interfering with the fuel staging process, thereby maintaining emission performance while improving combustor stability.
3Reliability
If low frequency dampers are installed to reduce pulsations, then pulsation control is improved, but large volumes are required increasing device complexity
Solution Approach 1:
The patent nests the resonator volumes and Helmholtz damper structure within the existing combustor transition piece geometry. The side wall extensions create resonator volumes that are integrated into the transition piece, utilizing the available space efficiently without requiring additional external volume, thus achieving low frequency pulsation control with compact dimensions.
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 decouples can-to-can thermo acoustic pulsations, increasing the lifetime of gas turbines and reducing emissions by utilizing a resonator volume connected to the hot gas flow path through a Helmholtz-damper, thereby suppressing multiple pulsation frequencies.
Implementation Method 1
The side wall extension at least partly encloses a resonator volume. The side wall extension comprises a resonator hole, which is configured as a neck of a Helmholtz-damper, which fluidly connects the resonator volume with the hot gas flow path.
Implementation Method 2
Combustor transition with a wall extension to provide space for a resonator volume arranged as a Helmholtz-damper for thermo acoustic decoupling of adjacent combustors
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a~4b
AI summary
The disclosure relates combustor transition (24) adapted to guide combustion gases in a hot gas flow path (15) extending between a can combustor (2) and a first stage of turbine (3) in a gas turbine (9). The combustor transition (24) comprises a duct having an upstream end adapted for connection to the can combustor (2) and an downstream end adapted for connection to a first stage of a turbine (3), wherein the downstream end comprises an outer wall (11), an inner wall (12), a first and a second side wall (21 a, 21 b). The combustor transition is, characterized in that at least one side wall (21 a, 21 b) has a side wall extension (20, 20a, 20b), which is extending in a downstream direction beyond the outlet (22). The side wall extension (20, 20a, 20b) at least partly encloses a first resonator volume (28) and at least one side wall extension (20, 20a, 20b) comprises a resonator hole (26), which is configured as a neck of a Helmholtz-damper. Besides the combustor transition (24) a gas turbine comprising such a combustor transition (24), a method for retrofitting a gas turbine (9) with such a combustor transition (24) as well as a method for borescope inspection of a GT with such a combustor transition are disclosed.