Combustor Panel Arrangement Mitigating Thermal Maldistribution
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Solution Overview
Problem
Gas turbine combustors face challenges with thermal maldistribution, leading to localized high-temperature zones or 'hot spots' that can reduce the usable life of the combustor due to uneven heat distribution and associated stress and strain, particularly in RQL combustion configurations where NOx formation is a concern.
Innovation Solution
The solution involves optimizing the arrangement of air admittance holes by determining a jet penetration distance Y, defined by the equation Y = D * j / (g + j * J), where D is the mean diameter, j is the jet flow, g is the gas flow, and J is the momentum flux ratio, to achieve fully penetrating flow and mitigate thermal maldistribution through strategic placement and design of heat shield panels and air admittance holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air admittance holes are used for cooling in a twin wall combustor, then thermal maldistribution and hot spots are reduced, but the complexity of the combustor structure increases due to the need for precise hole placement and dual wall configuration
Solution Approach 1:
The combustor is divided into an inner wall and outer wall structure, with the inner wall segmented into multiple sections. Air admittance holes are strategically placed at specific locations (e.g., at the downstream end of fuel injectors and at section transitions) to provide targeted cooling where thermal maldistribution occurs, rather than uniformly distributing holes throughout the entire structure.
Solution Approach 2:
Cooling air is admitted at specific localized positions where hot spots are most likely to form - particularly at the downstream end of fuel injector sections and at transitions between inner wall sections. This localized cooling approach addresses thermal maldistribution precisely where needed without requiring complex cooling systems throughout the entire combustor.
2Temperature
If cooling air is admitted through air admittance holes, then hot spots are mitigated, but the manufacturing precision requirements increase due to the need for precise hole placement and dual wall alignment
Solution Approach 1:
The inner wall is divided into multiple discrete sections that can be manufactured separately with standardized features. Air admittance holes are placed at specific locations relative to these sections (e.g., at section downstream ends and at fuel injector boundaries), allowing each section to be manufactured with consistent precision requirements rather than requiring the entire combustor to be manufactured as a single高精度 component.
Solution Approach 2:
The positions for air admittance holes are predetermined based on the combustion chamber geometry and thermal analysis. Holes are placed at specific locations that can be identified during the manufacturing process (e.g., at the downstream end of fuel injectors, at section transitions), allowing workers to locate and drill holes at these pre-determined positions without requiring complex real-time measurements.
3Strength
If the combustor uses a twin wall configuration with heat shield panels, then structural strength is improved, but the device complexity increases due to the additional components and assembly requirements
Solution Approach 1:
The heat shield panels are integrated with the inner wall sections, forming a combined structure that provides both thermal protection and structural support. The air admittance holes are incorporated into the inner wall/heat shield assembly rather than being separate components, reducing the total number of parts while maintaining the protective function.
Solution Approach 2:
The inner wall structure serves multiple functions: it acts as a heat shield protecting the combustor from high temperatures, provides structural support, and incorporates air admittance holes for cooling. This multi-functionality reduces the need for separate dedicated cooling systems and simplifies the overall combustor architecture.
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 approach effectively reduces thermal maldistribution, minimizing the formation of hot spots and promoting a more uniform temperature profile, thereby extending the combustor's lifespan and reducing NOx emissions by ensuring better cooling and mixing of combustion gases.
Implementation Method 1
Cooling air passes through the holes in the outer shell and then again through the holes in the inner liner, and finally into the combustion chamber
Implementation Method 2
The radially inward liner forms a heat shield
Implementation Method 3
a combustor for burning a hydrocarbon fuel in the presence of the pressurized air
Implementation Method 4
The associated air passages impart a swirl to inlet air entering the forward end of the combustion chamber at the bulkhead to provide rapid mixing of the fuel and inlet air
Implementation Method 5
determining a jet penetration distance Y, defined by the equation Y = D * j / (g + j * J), where D is the mean diameter, j is the jet flow, g is the gas flow, and J is the momentum flux ratio, to achieve fully penetrating flow
Data Source
Figure 1~3
Figure 2
Figure 4
AI summary
A combustor module (18) for a gas turbine engine is provided that includes a first annular liner assembly (26) extending along a longitudinal axis of the engine. The first annular liner assembly (26) includes a first annular support shell (52) and a plurality of first heat shield panels (48,50) coupled to the first annular support shell (52). The first heat shield panels (48,50) form a segmented ring defining a plurality of first axial seams (54) therebetween. The combustor module (18) further includes a bulkhead (30) coupled to the first annular liner assembly (26). The bulkhead (30) provides a plurality of fuel nozzles (38) for passing a first mass flow comprising fuel and air. The combustor module (18) further includes a second annular liner assembly (28) coupled to the bulkhead (30). The second annular liner assembly (28) is in spaced-apart generally coaxial relationship from the first annular liner assembly (26) by a channel height H. The second annular liner assembly (28) includes an air admittance hole (78) having a mean diameter D extending along a hole axis (80). The hole axis (80) is offset from the first axial seam (54) defined by the first heat shield panels (48,50).