Fuel Injector Heat Shield Air Layer Insulation
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Solution Overview
Problem
Fuel coking occurs in fuel injectors of gas turbine combustors, particularly near the combustion chamber, due to high temperatures, which existing technologies fail to effectively prevent.
Innovation Solution
A fuel injection device with a plane jet type fuel injector is designed to include a heat shield cover and air layer insulation to shield and insulate the fuel injection portion from heat, along with a radial gap and annular protrusions to reduce thermal and vibrational stress, and a fuel passage cover to prevent direct heat input and vibrational stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a plane jet type fuel injector is used to simplify the structure, then the device complexity is reduced, but fuel coking occurs due to high temperature exposure
Solution Approach 1:
A heat shield cover is introduced as an intermediary component between the combustion chamber and the fuel injection portion. This heat shield cover creates an air layer insulation barrier that mediates the thermal interaction, protecting the fuel injection portion from direct high-temperature exposure while maintaining the simplified plane jet injector structure.
Solution Approach 2:
The heat shield cover is extracted as a separate component from the fuel injection portion, allowing independent optimization of both elements. The heat shield cover can be specifically designed to provide thermal protection without complicating the fuel injection mechanism itself, thus preventing fuel coking while maintaining structural simplicity.
2Temperature
If the heat shield cover is positioned close to the fuel injection portion to provide effective shielding, then temperature increase is suppressed, but vibrational stress increases at the joining portion
Solution Approach 1:
Annular protrusions are provided on the fuel injection portion in advance to define radial gaps with the heat shield cover. This preliminary structural arrangement prevents direct contact and reduces vibrational stress at the joining portion while maintaining the heat shield cover's thermal protection function.
Solution Approach 2:
The heat shield cover is designed to cover only the combustion chamber-side portion of the fuel injection portion, providing localized thermal protection where it is most needed. The radial gap configuration provides localized stress reduction at critical joining areas, optimizing both thermal and mechanical performance.
3Stability of the object's composition
If the cover support portion is joined to the fuel flow path portion to provide structural support, then the heat shield cover is stabilized, but heat input to the fuel flow path portion increases
Solution Approach 1:
The support structure transitions from direct axial contact to radial gap configuration with annular protrusions. This dimensional change in the support arrangement allows the heat shield cover to be stabilized through radial positioning rather than direct axial contact, reducing heat transfer to the fuel flow path portion while maintaining structural stability.
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
Effectively suppresses temperature increase and prevents fuel coking in the fuel injector, ensuring stable operation and reducing the risk of backfire by maintaining an appropriate air flow and insulation.
Implementation Method 1
the portion, of the fuel injection portion, which is on the combustion chamber side and which is subjected to a particularly high temperature in the fuel injector is shielded from heat by the heat shield cover, and is insulated from heat by the air layer formed between the heat shield cover and the fuel injection portion
Data Source
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AI summary
A fuel injection device for injecting an air-fuel mixture to a combustion chamber in a combustor of a gas turbine engine includes a fuel injector which is arranged on an axis of the fuel injection device. The fuel injector includes a fuel injection portion for injecting fuel in the radial direction of the fuel injection device, a fuel flow path portion forming a passage through which fuel is supplied to the fuel injection portion, and a heat shield cover that covers an end portion facing toward the combustion chamber side of the fuel injection portion such that an air layer is formed between the heat shield cover and the end portion.