Fuel Spray Nozzle Splitter Wall Cooling Film Design
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Solution Overview
Problem
Fuel spray nozzles in gas turbine engines face degradation and reduced service life due to high metal temperatures caused by hot combustion gases, particularly in nozzles with a coaxial arrangement of an inner pilot airblast fuel injector and an intermediate air swirler passage.
Innovation Solution
A fuel spray nozzle design with a coaxial arrangement of an inner pilot airblast fuel injector and an outer mains airblast fuel injector, featuring an intermediate air swirler passage sandwiched between outer and inner swirler passages, utilizing annular splitter walls with convergent and divergent sections to create a cooling film and maintain swirling air flow, which convectively cools the nozzle surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an intermediate air swirler passage is added between pilot and mains injectors, then fuel-air mixing and atomization are improved, but metal temperature increases and service life decreases
Solution Approach 1:
A coolant passage is introduced as an intermediary element between the intermediate air swirler passage and the splitter walls. This passage delivers coolant fluid to cooling outlets positioned adjacent to the splitter walls, creating a thermal barrier that protects the metal components from excessive temperatures while preserving the intermediate passage's mixing function
Solution Approach 2:
The invention utilizes hydraulic cooling by circulating coolant fluid through the coolant passage and delivering it via cooling outlets. The coolant forms a protective film on the splitter walls, using fluid dynamics to manage heat transfer and reduce metal temperatures
2Temperature
If coolant passages and cooling outlets are added to protect from hot gases, then metal temperature is reduced, but device complexity increases
Solution Approach 1:
The intermediate air swirler passage serves multiple functions: it provides fuel-air mixing and atomization while also acting as a conduit for coolant delivery. The cooling outlets are integrated into the existing nozzle structure rather than being separate components, reducing overall system complexity
Solution Approach 2:
The coolant passage is merged with the intermediate air swirler passage structure, and the cooling outlets are integrated into the splitter wall assembly. This consolidation combines the cooling function with existing structural elements, minimizing additional complexity
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 design effectively reduces metal temperatures of the splitter walls, enhancing the service life of the nozzle by forming and maintaining a cooling film, and maintaining swirling flow to prevent separation and ensure effective cooling.
Implementation Method 1
The swirling air passing through the air swirler passages can help to protect the nozzle from contact with hot combustion gases, and can also convectively cool surfaces of the nozzle, extracting heat absorbed from flame radiation.
Implementation Method 2
The swirling air passing through the air swirler passages can help to protect the nozzle from contact with hot combustion gases, and can also convectively cool surfaces of the nozzle, extracting heat absorbed from flame radiation.
Implementation Method 3
the outer surface profile of the first splitter wall and the inner surface profile of the second splitter wall having respective convergent sections (the convergence being relative to the overall axial direction of flow through the injector) which face each other to produce a convergent portion of the intermediate air swirler passage
Data Source
AI summary
Nozzle for engine has coaxial arrangement of inner pilot and outer mains airblast fuel injectors and intermediate air-swirler passage sandwiched between the outer and inner air-swirler passages of the pilot and mains airblast fuel injectors, respectively. The nozzle has an annular first-splitter wall separating the pilot outer air-swirler passage from the intermediate one. An outer surface profile of the first-splitter wall defines radially inner side of the intermediate air-swirler passage. The nozzle has an annular second-splitter wall separating the intermediate air-swirler passage from mains inner air-swirler passage. An inner surface profile of second-splitter wall defines radially outer side of intermediate air-swirler passage. The outer and inner surface profile of the first and second splitters walls, respectively, have convergent sections facing each other forming convergent portion of the intermediate air-swirler passage. The inner surface profile of the second-splitter wall has a divergent section downstream of its convergent section.