Distributed Spark Igniter for Gas Turbine Combustor
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Solution Overview
Problem
Prior gas turbine engine igniters face difficulties in igniting the air-fuel mixture due to recirculation, large fuel and air gradients, and turbulence, leading to limited spark kernel range and lifespan, and inefficient combustion.
Innovation Solution
A distributed spark igniter system with a recessed terminal and a separate, diametrically opposed electrode creates a pulsed electrical arc between the igniter and the electrode, allowing for a wider ignition area and more efficient combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a capacitor discharge ignition system is used to create a local spark kernel, then highly-concentrated energy is introduced into the combustion chamber, but the spark kernel has limited range and lifespan due to recirculation, large fuel and air gradients, and turbulence
Solution Approach 1:
The ignition system is segmented into two separate components: a capacitor discharge igniter that creates an initial spark kernel, and a separate electrode that sustains the combustion. This segmentation allows the igniter to provide concentrated energy while the electrode maintains the flame, overcoming the limited lifespan of a single spark kernel in turbulent conditions
Solution Approach 2:
The separate electrode acts as an intermediary that receives the initial spark from the capacitive igniter and translates it into a sustained electrical arc. This intermediary component bridges the gap between the brief spark kernel and the continuous combustion requirement, extending the effective ignition duration
2Use of energy by moving object
If a capacitor discharge ignition system is used, then highly-concentrated energy is introduced, but the design and aerodynamics must provide proper air-fuel stoichiometry near the kernel which is difficult given how fuel and air are introduced
Solution Approach 1:
By separating the ignition function into two components (capacitive igniter and separate electrode), the system reduces the requirement for precise air-fuel stoichiometry at a single point. The extended electrical arc creates a larger ignition zone that can accommodate variations in fuel-air mixing, making the system more tolerant of aerodynamic design constraints
Solution Approach 2:
The invention transitions from a point-source spark kernel to a line-source electrical arc by positioning the electrode opposite the igniter. This dimensional change from 0D to 1D ignition creates a larger effective ignition volume, reducing the sensitivity to local air-fuel ratio variations and simplifying the aerodynamic design requirements
3Productivity
If a single igniter is used to ignite the air-fuel mixture, then ignition is achieved, but the burn is not even throughout the combustion chamber and thermal stress is high
Solution Approach 1:
The combustion chamber is effectively divided into two ignition zones by positioning the electrode opposite the igniter. This creates a more distributed combustion pattern that promotes even burning throughout the chamber, reducing localized thermal stress concentrations and improving overall thermal management
Solution Approach 2:
The system uses asymmetric positioning of the electrode relative to the igniter to create an optimized electrical arc path that promotes more uniform heat distribution. The electrode is specifically positioned to maximize the ignition area and promote even combustion, rather than using a symmetric single-point ignition approach
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 achieves a more even burn throughout the combustion chamber, reducing thermal stress on the igniter and combustor, extending their lifespan and improving fuel efficiency.
Implementation Method 1
an electrical potential is created between the igniter and the electrode to produce an electric arc therebetween
Implementation Method 2
create a local spark kernel or plasma cloud to introduce highly-concentrated energy into the combustion chamber
Data Source
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AI summary
An ignition system for a combustor of a gas turbine engine is disclosed. The ignition system may include an igniter operatively associated with the combustor, and an electrode operatively associated with the combustor and spaced from the igniter, wherein an electrical potential is created between the igniter and the electrode to produce an electric arc therebetween.