Fuel Injecting Device Axial Rearward Injection Coking Prevention
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Solution Overview
Problem
Conventional fuel injection devices for gas turbine engines face challenges in reducing NOx emissions and preventing coking in main fuel injectors, particularly during low power operations, while maintaining a compact size and stable combustion.
Innovation Solution
A fuel injection device design featuring a pilot fuel injector on the axis and an annular main fuel injector with circumferentially spaced injection holes, utilizing an annular fuel passage forming portion, inner, and outer ring portions to create separate fuel supply passages, which allows for axial rearward fuel injection and cooling of the main fuel supply passage during low power operations, preventing coking and maintaining a small radial dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the main fuel injector is not operated during low power operation to reduce fuel consumption, then fuel economy is improved, but coking occurs in the main fuel supply passage due to heat from high-temperature air
Solution Approach 1:
The pilot fuel supply passage acts as an intermediary cooling channel. Fuel flowing through the pilot fuel supply passage serves as a cooling medium that prevents coking in the main fuel supply passage during low power operation, even when the main fuel injector is not operating.
Solution Approach 2:
The pilot fuel supply passage serves dual functions: (1) supplying fuel to the pilot fuel injector for stable combustion during low power operation, and (2) cooling the main fuel supply passage to prevent coking when the main fuel injector is not in use.
2Productivity
If the main fuel injector is designed to inject fuel radially outward, then combustion coverage is improved, but the radial dimension of the device increases
Solution Approach 1:
Instead of injecting fuel radially outward from the main fuel injector, the invention inverts the approach by using the pilot fuel injector on the axis to inject fuel axially rearward, achieving combustion coverage through the pilot flame while keeping the main fuel injector compact in the radial direction.
Solution Approach 2:
The invention shifts the combustion coverage strategy from radial expansion to axial rearward injection. The main fuel injection holes are configured to inject fuel axially rearward, changing the dimension of combustion spread from radial to axial, thereby maintaining a small radial footprint.
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 effectively prevents coking in the main fuel supply passage, maintains a compact radial size, and ensures stable combustion by using the pilot fuel supply passage to cool the main fuel supply passage, thereby addressing the limitations of conventional devices.
Implementation Method 1
allows the main fuel supply passage to be cooled by fuel flowing through the pilot fuel supply passage
Data Source
AI summary
A fuel injection device for a gas turbine combustor includes a pilot fuel injector disposed on an axis of the fuel injection device; an annular main fuel injector encircling the pilot fuel injector; and a plurality of main fuel injection holes formed in the main fuel injector and spaced circumferentially from each other for injecting fuel axially rearward. The main fuel injector includes an annular fuel passage forming portion, an inner ring portion on an inner peripheral side of the fuel passage forming portion, and an outer ring portion on an outer peripheral side of the fuel passage forming portion. One of a space between the fuel passage forming portion and the inner ring portion and a space between the fuel passage forming portion and the outer ring portion forms a pilot fuel supply passage, and the other one forms a main fuel supply passage.