Annular Combustor Flange Diameter Ratios for Leakage Control
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Solution Overview
Problem
Annular combustors in gas turbine engines face challenges in reducing leakage through joints while maintaining easy assembly, as loose fits lead to undesirable leakage and tight fits hinder assembly, affecting combustion efficiency and emission control.
Innovation Solution
The design incorporates specific diameter ratios between flanges at joints, along with potential interference fits and thermal management, to control leakage while allowing for easy assembly, using ratios R1 and R2 to define optimal gap sizes and using keyhole slots for thermal expansion facilitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a loose fit is used between flanges to facilitate assembly, then ease of assembly is improved, but gas leakage through joints increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio between the inner diameter of the outer shell flange and the outer diameter of the inner shell flange. By optimizing this dimensional parameter within a specific range, the design achieves both easy assembly and reduced gas leakage, resolving the contradiction between assembly ease and leakage prevention.
2Loss of energy
If a tight fit is used between flanges to reduce leakage, then gas leakage is reduced, but assembly difficulty increases
Solution Approach 1:
The patent resolves this contradiction by changing the dimensional parameters of the flanges, specifically by controlling the ratio between the inner diameter of the outer shell flange and the outer diameter of the inner shell flange. This parameter optimization allows the joints to maintain low leakage while remaining easy to assemble.
3Loss of energy
If precise diameter ratios are specified for flanges to control leakage, then gas leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent addresses this contradiction by selecting a specific ratio range for the flange diameters that balances leakage control with manufacturability. By defining the ratio between the inner diameter of the outer shell flange and the outer diameter of the inner shell flange within an optimized range, the design achieves effective leakage prevention while maintaining reasonable manufacturing precision requirements.
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 gas leakage through the joints, maintaining combustion efficiency and assembly ease by optimizing flange diameters and thermal expansion, achieving a target nominal leakage area of 0.155 square inches or less.
Implementation Method 1
An interference fit between the radially outer hood flange and the first flange. An interference fit between the radially inner hood flange and the second flange.
Implementation Method 2
heating at least one of the annular outer shell, the annular inner shell and the bulkhead at a temperature of at least 240° F./116° C.; heating the annular outer shell at a temperature of 240° F./116° C., cooling the annular inner shell at a temperature of −275° F./−171° C., and heating the bulkhead at a temperature of 350° F./177° C.
Data Source
AI summary
An annular combustor includes an annular outer shell that includes a first flange that defines an inner diameter IDOS and an annular inner shell that includes a second flange that defines an outer diameter ODIS. An annular hood includes a radially outer hood flange and a radially inner hood flange. A bulkhead includes a radially outer bulkhead flange that defines an outer diameter ODB and a radially inner bulkhead flange that defines an inner diameter IDB. The first flange is secured at a radially outer joint between the radially outer hood flange and the radially outer bulkhead flange. The second flange is secured at a radially inner joint between the radially inner hood flange and the radially inner bulkhead flange. The IDOS and the ODB define a ratio R1 of IDOS/ODB that is 0.998622-1.001129, and the IDB and the ODIS define a ratio R2 of IDB/ODIS that is 0.998812-1.001388.