Gas Turbine Combustor Helmholtz Damping Cooling Chamber
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Solution Overview
Problem
Gas turbines face structural damage and increased NOx emissions due to thermo-acoustic pressure oscillations, which traditional passive damping structures fail to adequately address, often requiring cooling air diversion that compromises turbine lifetime and increases emissions.
Innovation Solution
A combustor design with integrated hollow elements acting as Helmholtz dampers, connected to the liner and outer cover plate, forming a cooling chamber that dissipates heat and damps pressure oscillations while maintaining efficient cooling and reducing NOx emissions by using calibrated ducts and optional damping material within the damping volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive damping structures are added to the combustor, then pressure oscillations are damped, but cooling air must be diverted from other regions causing increased operating temperature and reduced lifetime
Solution Approach 1:
The damping structure is merged with the cooling chamber structure, where the hollow elements form both the damping volumes and the cooling passages. This integration eliminates the need for separate damping structures that would require additional cooling air, as the same cooling air flowing through the cooling chamber also cools the damping elements.
Solution Approach 2:
The cooling air serves dual functions: it cools the liner and simultaneously cools the damping structures through the integrated cooling chamber. The hollow elements act as both damping volumes and heat exchange surfaces, allowing a single cooling air flow to perform multiple cooling tasks without diverting air from other regions.
2Temperature
If cooling air is diverted from the combustor, then damping structures are cooled, but flame temperature increases thus increasing NOx emissions
Solution Approach 1:
The damping structure is integrated into the cooling chamber, allowing the cooling air to cool both the liner and damping structures simultaneously without being removed from the combustor. This prevents the increase in flame temperature that would result from reducing combustor cooling air, thereby controlling NOx emissions.
Solution Approach 2:
The cooling chamber acts as an intermediary that allows cooling air to reach the damping structures without being extracted from the combustor. The calibrated ducts provide a controlled path for cooling air to enter the damping volumes, enabling heat transfer to the damping structures while maintaining combustor temperature control.
3Volume of moving object
If damping structures are incorporated into the combustor, then space utilization improves, but integration complexity increases
Solution Approach 1:
The damping structure is merged with the existing cooling chamber and liner assembly, utilizing the available space within the combustor rather than adding external components. The hollow elements are positioned within the cooling chamber, making use of the interstitial space between the liner and outer cover plate.
Solution Approach 2:
The hollow damping elements are nested within the cooling chamber structure, with each hollow element containing a damping volume that is accessible through calibrated ducts. This nested arrangement allows the damping function to be embedded within the existing combustor geometry without adding external complexity.
4Reliability
If traditional damping arrangements are used, then pressure oscillations are damped, but they are functionally separated from other combustor components making incorporation difficult
Solution Approach 1:
The damping structure is merged with the cooling chamber assembly, forming an integrated unit that is manufactured and installed as part of the combustor structure. The hollow elements are positioned within the cooling chamber and secured to the liner or outer cover plate, creating a unified assembly that simplifies manufacturing and installation.
Solution Approach 2:
The integrated structure serves multiple functions: the cooling chamber provides cooling passages, the hollow elements provide damping volumes, and the calibrated ducts provide access to the damping volumes. This multi-functional integration eliminates the need for separate damping components that would require additional installation steps.
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 integrated damping system effectively reduces pressure oscillations and maintains efficient cooling, extending gas turbine lifetime while controlling NOx emissions by dissipating heat and regulating pressure oscillation frequencies through calibrated ducts and adjustable damping volumes.
Implementation Method 1
Each hollow element defines a damping volume connected to the inner of the combustion chamber via a calibrated duct
Implementation Method 2
The combustor has a cooling air circulation path defined in the interposed cooling chamber and the hollow elements are arranged to be cooled by the cooling air circulating in the cooling chamber
Implementation Method 3
Each hollow element defines a damping volume connected to the inner of the combustion chamber via a calibrated duct
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The combustor (1) has at least a portion (4) comprising an inner liner (5) and an outer cover plate (6) defining with the inner liner (5) an interposed cooling chamber (7). From the liner (5) a plurality of hollow elements (9, 9f) protruding into the cooling chamber (7) extend. Each hollow element (9, 9f) defines a damping volume (10) connected to the inner of the combustor (1) via a calibrated duct (11). During operation the hollow elements (9) damp pressure pulsations and, in addition, also transfer heat.