Fuel Spray Nozzle Uniform Distribution Additive Manufacturing
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Solution Overview
Problem
Conventional fuel spray nozzles for gas turbine engines face challenges in achieving uniform and suitable swirling of fuel flows due to manufacturing restrictions, particularly in the prefilming surface of the mains flow circuit, which affects combustion efficiency.
Innovation Solution
The fuel spray nozzle design includes a flow circuit with a gallery, circumferentially-spaced restrictor passages, and conditioning passages that decouple flow distribution and swirling functions, using additive layer manufacturing to create an atomiser subassembly that allows for a high swirl number fuel flow with low losses, where the restrictor passages produce pressure differentials and the conditioning passages impart a circumferential component to the fuel flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If circumferential row of flow restrictors is used to provide swirling flow, then fuel flow can be evenly distributed around the nozzle, but configuring restrictors to achieve uniform fuel flow and required degree of swirl at the prefilming surface is difficult due to manufacturing restrictions
Solution Approach 1:
The flow circuit is divided into multiple separate flow paths, each with its own flow restrictor and prefilming surface section. This segmentation allows each restrictor to be independently configured and manufactured, simplifying the overall manufacturing process while maintaining uniform fuel flow distribution around the nozzle.
Solution Approach 2:
Each flow path is given locally optimized characteristics with specific restrictor geometries and prefilming surface configurations tailored to its position around the nozzle. This local quality approach ensures that each section contributes appropriately to the overall uniform swirling flow pattern.
2Ease of manufacture
If conventional machining and brazing processes are used to manufacture the atomiser subassembly, then manufacturing is straightforward, but the ability to achieve high swirl number fuel flow with low losses is limited
Solution Approach 1:
The conventional mechanical machining and brazing process is replaced with additive layer manufacturing technology. This substitution enables the creation of complex internal flow path geometries and smooth transitions that reduce flow separation and turbulence, achieving high swirl number fuel flow with significantly lower energy losses while maintaining manufacturing feasibility.
3Quantity of substance
If the prefilming surface is made larger to accommodate greater flow rate variation, then more fuel can be handled, but the difficulty in achieving uniform swirl and flow distribution increases
Solution Approach 1:
The large prefilming surface is divided into multiple smaller prefilming surfaces, each fed by its own dedicated flow path with individual flow restrictor. This segmentation allows each section to maintain uniform flow distribution while the aggregate capacity handles greater total fuel flow rates.
Solution Approach 2:
Each flow path and prefilming surface section is locally optimized for its specific operating conditions and position around the nozzle. This local quality approach ensures uniform swirl and flow distribution across the entire large surface area, even as total fuel flow capacity increases.
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 design ensures reliable and efficient atomization of fuel into fine droplets, improving combustion efficiency by providing a uniform swirling flow with reduced losses and accommodating varying flow conditions.
Implementation Method 1
the restrictor passages form flow restrictions which in use produce a pressure differential between the gallery and the spin chamber to evenly circumferentially distribute the fuel flow between the restrictor passages
Implementation Method 2
plural conditioning passages which respectively receive the portions of the fuel flow from the restrictor passages and are configured to impart a circumferential component to their respective portions of the fuel flow
Implementation Method 3
an annular spin chamber which receives and recombines the respective portions of the fuel flow from the conditioning passages to form the swirling fuel flow
Implementation Method 4
an annular prefilming surface downstream of the annular exit port, and configured such that the swirling fuel flow received from the exit port spreads, as a film of fuel, across the prefilming surface
Implementation Method 5
one or more swirling air flows generated by the nozzle shear the fuel film towards a trailing edge of the prefilming surface and atomise the fuel film into a spray of fine droplets
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A fuel spray nozzle (40) for generating a spray of atomised liquid fuel in a combustor of a gas turbine engine (10). The nozzle (40) includes a flow circuit (50) that has in flow series: a gallery (52) that receives fuel flow, plural circumferentially-spaced restrictor passages (53) arranged in a row around the nozzle, plural conditioning passages (54) configured to impart a circumferential component to their respective portions of the fuel flow, and an annular spin chamber (55) which forms a swirling fuel flow which is discharged at an exit port (56). The restrictor passages (53) form flow restrictions which in use produce a pressure differential between the gallery (52) and the spin chamber (55) to evenly circumferentially distribute the fuel flow between the restrictor passages (53). The conditioning passages (54) have increased flow cross-sectional areas relative to the flow cross-sectional areas of the restrictor passages (53), such that the restrictor passages (53) produce substantially all of the pressure differential between the gallery (52) and the spin chamber (55).