Gas Turbine Fuel Injector Pilot Assembly Cross-Talk Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas turbine fuel injectors experience cross-talk issues due to variations in air-fuel mixture and pressure, leading to fuel and combustion gas ingestion between inactive and active fuel lines, causing system damage and instability.
Innovation Solution
A pilot assembly within the fuel injector includes a longitudinal passageway with a flow restriction section and strategically positioned nozzles for liquid and gaseous fuel, along with compressed air, to manage pressure and velocity, reducing cross-talk by positioning assist air and gas fuel nozzles away from the combustor and upstream of high-pressure air flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fuel lines are fluidly coupled to enable fuel switching between liquid and gaseous fuel, then the gas turbine engine can operate using different fuel types, but cross-talk occurs when one fuel line is inactive causing fuel and combustion gas ingestion between injectors
Solution Approach 1:
The patent extracts and removes the harmful cross-talk flow path by positioning the inactive fuel line outlets away from active fuel lines and combustor inlets. The inactive fuel line outlets are directed toward the center of the combustor where they do not interfere with active fuel injection, effectively separating the harmful flow from the useful flow paths.
Solution Approach 2:
The patent introduces compressed air as an intermediary substance to purge and protect against cross-talk. Compressed air is injected through nozzles positioned near the inactive fuel line outlets to create a protective barrier that prevents combustion gases and fuel from ingesting through inactive lines, using a harmless fluid to block harmful flow paths.
2Reliability
If multiple fuel injectors are used to maintain stable flame and meet NOx emissions, then combustion stability is improved, but pressure variations between injector outlets cause cross-talk
Solution Approach 1:
The patent segments the fuel injection system into distinct zones: active fuel lines with outlets positioned at the combustor periphery, inactive fuel lines with outlets directed toward the combustor center, and compressed air injection points strategically located to create protective barriers. This spatial segmentation prevents pressure-induced cross-talk between adjacent injectors.
3Ease of operation
If fuel lines remain connected during fuel switching, then quick fuel type changeover is enabled, but the connected lines allow ingestion of fuel and hot combustion gases
Solution Approach 1:
The patent implements preliminary protective action by pre-positioning compressed air injection nozzles at strategic locations along the inactive fuel lines. Before combustion gases can ingress through inactive lines, compressed air is already present creating a protective barrier, preventing hot gas and fuel ingestion while maintaining ready-to-switch fuel line connections.
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 solution effectively minimizes cross-talk by ensuring only clean compressed air is ingested during potential ingestion events, reducing the likelihood of fuel and gas ingestion and maintaining system stability and efficiency across different fuel types.
Implementation Method 1
The flow restriction section may be a narrowed section of the longitudinal passageway, in which an upstream side of the flow restriction section may have compressed air at substantially the compressor discharge pressure and a downstream side may have air at a lower pressure and a higher velocity
Implementation Method 2
A compressed air inlet that is configured to direct air compressed by a compressor of the engine to a compressor discharge pressure into the longitudinal passageway without a substantial loss of pressure
Data Source
AI summary
A pilot assembly for a fuel injector of a gas turbine engine may include a longitudinal passageway having an outlet end. A mass flow in the longitudinal passageway may generally flow towards the outlet end during operation of the engine. The pilot assembly may also include a liquid fuel nozzle that is positioned to direct a mixture of liquid fuel and air near the outlet end, and a compressed air inlet that is configured to direct air compressed by a compressor of the engine to a compressor discharge pressure into the longitudinal passageway without a substantial loss of pressure. The longitudinal passageway may also include a flow restriction section. The flow restriction section may be a narrowed section of the longitudinal passageway, in which an upstream side of the flow restriction section may have compressed air at substantially the compressor discharge pressure and a downstream side may have air at a lower pressure and a higher velocity. The pilot assembly may further include a nozzle for injecting one of assist air or gaseous fuel into the longitudinal passageway. The nozzle may be positioned at the flow restriction section or on an upstream side of the flow restriction section to reduce cross-talk.