Carbureted Fuel Injection System for Gas Turbine Augmentor Stability
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Solution Overview
Problem
Gas turbine engines face challenges in achieving deep fuel penetration for augmentor efficiency and stability, which can lead to flame instability and 'screech' due to high fuel flow rates.
Innovation Solution
A fuel injection system with a vane and air channel that partially premixes and prevaporizes fuel with a secondary airflow before injection into the airflow path, using a combination of fuel nozzles and spraybars to optimize fuel distribution and stability, including a Carbureted Fuel Injection System (CFIS) and Jet-in-Cross Flow (JCF) system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel flow rate is increased to achieve deep fuel penetration and improve augmentor efficiency, then augmentor efficiency and supplemental thrust magnitude are improved, but flame stability deteriorates and augmentor instabilities (screech) increase
Solution Approach 1:
The patent applies preliminary action by pre-mixing fuel with air in the air channel before the fuel enters the augmentor section. The fuel nozzle injects fuel into the air channel where it mixes with secondary airflow, and the vane structure provides preliminary vaporization and distribution. This preliminary preparation of the fuel-air mixture occurs upstream in the air channel, allowing the fuel to be better prepared before entering the main combustion zone, thereby enabling stable combustion at higher fuel flow rates and reducing screech instabilities.
2Stability of the object's composition
If fuel penetrates deep into core exhaust gases to improve mixing and augmentor efficiency, then fuel-air mixing is improved, but flameholder stability deteriorates due to fuel flow rate effects
Solution Approach 1:
The patent uses the air channel and secondary airflow as an intermediary medium. Instead of injecting fuel directly into the core exhaust gases, the fuel is first injected into the air channel where it mixes with secondary airflow. This intermediary mixing zone allows controlled fuel-air preparation, and the mixed fuel then enters the augmentor section. The intermediary air channel acts as a buffer that improves mixing quality while protecting flameholder stability by controlling the fuel introduction process.
3Power
If high fuel flow rate is used to increase supplemental thrust, then thrust magnitude is improved, but augmentor instabilities (screech) increase
Solution Approach 1:
The patent replaces a purely direct mechanical injection system with a more sophisticated carburetor-like system that uses fluid dynamics principles. Instead of simply injecting fuel at high flow rates, the system uses the air channel to create a carburetor effect where secondary airflow draws fuel through the air channel, providing preliminary mixing and vaporization. This substitution of the injection mechanism reduces instabilities while maintaining the required thrust level.
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 system enhances fuel-air mixture preparation, reducing combustion instability and 'screech' by optimizing fuel distribution, ensuring stable operation across various engine conditions while maintaining efficiency and minimizing external geometry changes.
Implementation Method 1
inject fuel into the air channel to at least partial premix and prevaporize the fuel with a secondary airflow
Implementation Method 2
inject fuel into the air channel to at least partial premix and prevaporize the fuel with a secondary airflow
Implementation Method 3
an interior of the vane receives the secondary airflow such that the interior is at a higher pressure than an airflow within the airflow path
Data Source
AI summary
A fuel injection system for a gas turbine engine includes a vane in an airflow path within the gas turbine engine, the vane includes an air channel with an outlet in communication with the airflow path; and a fuel nozzle within the vane operable to inject fuel into the air channel to at least partially premix and prevaporize the fuel with a secondary airflow from within the vane in the air channel prior to entry into the airflow path through the outlet. A method of injecting fuel within a gas turbine engine includes at least partially premixing and prevaporizing fuel with a secondary airflow from within a vane in an air channel within the vane, the vane within an airflow path of the gas turbine engine.