Lean Burn Injector Dual Pilot Circuits
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Solution Overview
Problem
Conventional staged fuel injectors for gas turbine engines face challenges in providing thermally efficient, low emissions operation over a wide range of conditions, particularly during low power operation, where carbon formation and high fuel delivery pressure requirements are concerns, and there is a need for easier design and operation with reduced carbon formation.
Innovation Solution
The fuel injector design includes a nozzle body with a main fuel circuit, an air circuit, a primary pilot fuel circuit, and a secondary pilot fuel circuit, featuring prefilming air-blast atomizers and pressure swirl atomizers, which allows for staged operation in a pilot-only mode with lower fuel delivery pressure requirements and reduced carbon formation risks by separating fuel zones and using thermal management techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional staged fuel injectors operate in pilot-only mode during low power conditions, then emissions can be reduced, but carbon formation increases and fuel delivery pressure requirements increase
Solution Approach 1:
The pilot fuel circuit is divided into two separate circuits: a first pilot fuel circuit and a second pilot fuel circuit. This segmentation allows each circuit to be optimized for different operating conditions, with the second circuit specifically designed to prevent carbon formation during low power pilot-only operation through its specific geometric configuration and flow characteristics
Solution Approach 2:
Each pilot fuel circuit is designed with different local characteristics - the first pilot fuel circuit has specific flow parameters optimized for certain conditions, while the second pilot fuel circuit has different flow parameters and geometric features optimized for preventing carbon formation during low power operation, allowing each region to have the quality needed for its specific function
2Object-generated harmful factors
If conventional staged fuel injectors operate in pilot-only mode during low power conditions, then emissions can be reduced, but fuel delivery pressure requirements increase
Solution Approach 1:
The pilot fuel circuit is divided into two separate circuits with different flow characteristics and pressure requirements. The second pilot fuel circuit is specifically designed to operate efficiently at lower pressures during low power conditions, reducing the overall fuel delivery pressure requirement while maintaining emission control capabilities
Solution Approach 2:
The dual pilot circuit system allows dynamic selection and optimization of fuel delivery paths based on operating conditions. During low power pilot-only mode, the system can utilize the second pilot fuel circuit which is optimized for lower pressure operation, thereby reducing the fuel delivery pressure requirements compared to conventional single-circuit designs
3Duration of action of stationary object
If the fuel circuit is protected from carbon formation during low power operation, then injector life is extended, but device complexity increases due to active cooling or insulation requirements
Solution Approach 1:
The second pilot fuel circuit is designed with geometric features and flow characteristics that inherently prevent carbon formation through its flow patterns and pressure distribution. The circuit configuration itself provides the carbon prevention function without requiring external cooling systems or insulation, allowing the system to protect itself from carbon deposition during low power operation
Solution Approach 2:
The carbon prevention function is extracted from complex active cooling or insulation systems and integrated directly into the fuel circuit geometry and flow characteristics. The second pilot fuel circuit's design inherently provides carbon formation prevention through its structural features, eliminating the need for separate protection systems
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 enables efficient operation up to 50%-70% throttle level in pilot-only mode with reduced emissions and lower fuel delivery pressure, while preventing carbon formation and extending injector life through effective thermal management and staged fuel injection.
Implementation Method 1
The main fuel delivery system utilizes a series of discrete atomizers that spray radially outward into a swirling cross-flow of air
Implementation Method 2
a pressure swirl atomizer sprays liquid fuel onto a filming surface where the liquid film is stripped off into droplets
Implementation Method 3
Lean burning results in lower flame temperatures than would occur with stoichiometric burning. Since the production of NOX is a strong function of temperature, a reduced flame temperature results in lower levels of NOX
Implementation Method 4
Measures must be taken to control temperatures in the stagnant fuel circuit to prevent coking within the injector
Data Source
AI summary
A fuel injector for a gas turbine engine includes a nozzle body defining a central axis and having a main fuel circuit. An air circuit is formed within the nozzle body inboard of the main fuel circuit. A primary pilot fuel circuit is formed within the nozzle body inboard of the air circuit. A secondary pilot fuel circuit is formed within the nozzle body inboard of the air circuit and outboard of the primary pilot fuel circuit.