Pilot Fuel Injector Mixer Assembly for Gas Turbine Combustion
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Solution Overview
Problem
Current gas turbine engine combustors face challenges in minimizing undesirable combustion products like NOx, HC, and CO, as existing fuel nozzles, such as the Airblast-Simplex type, have limited fuel flow range and reduced atomization quality at low flows, and are susceptible to coking, especially with increasing pressure ratios.
Innovation Solution
The proposed solution involves a mixer assembly with a primary and secondary fuel injector, where the primary fuel injector uses a Pure Airblast type nozzle with a central axis for stable fuel delivery and a secondary injector for enhanced fuel flow, accompanied by a primary air jet to direct air streams effectively, and includes a heat shield to minimize coking risks, achieving improved fuel flow and atomization without sacrificing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Airblast-Simplex fuel nozzle is used for pilot mixer, then fuel injection is achieved through combination of fuel pressure drop and airblast effect, but fuel flow range is limited and atomization quality is reduced at low flows
Solution Approach 1:
The fuel injection system is segmented into multiple nozzles (first nozzle and second nozzle) with different injection characteristics. The first nozzle provides stable atomization at low flows, while the second nozzle enhances fuel flow capacity, allowing the system to achieve both wide flow range and consistent atomization quality across all operating conditions.
Solution Approach 2:
The invention changes the parameters of the fuel injection system by introducing nozzles with different flow coefficients and injection patterns. This allows optimization of atomization quality at low flows while simultaneously increasing the overall fuel flow range, resolving the trade-off between these two parameters.
2Quantity of substance
If fuel pressure drop is relied upon for fuel injection, then injection is achieved, but fuel flow range is reduced within limits of pump capacity at high flows
Solution Approach 1:
The injection system is divided into multiple nozzles that share the total fuel flow requirement. This segmentation allows each nozzle to operate within its optimal flow range, maintaining injection stability while collectively achieving a broader fuel flow range that accommodates both low and high flow conditions.
Solution Approach 2:
The multi-nozzle system serves multiple functions simultaneously: the first nozzle ensures stable atomization at low flows, while the second nozzle provides additional flow capacity at high flows. This multi-functional approach allows the system to maintain reliability across the entire operating range.
3Object-generated harmful factors
If single stage combustion is used, then simpler combustor design is achieved, but undesirable combustion products (NOx, HC, CO) cannot be minimized simultaneously
Solution Approach 1:
The combustion process is segmented into two stages with distinct fuel injection systems. The first stage uses the first nozzle for stable combustion at all operating conditions, while the second stage adds supplementary fuel injection for high flow conditions. This segmentation enables control of combustion products to meet emissions requirements while maintaining a relatively simple overall combustor design.
4Manufacturing precision
If pilot mixer uses ABS fuel injector, then fuel pre-filming and atomization is achieved, but spray stability and atomization quality at low flows are reduced
Solution Approach 1:
The spray generation function is segmented between two nozzles with different characteristics. The first nozzle is specifically optimized for stable spray generation at low flows, while the second nozzle supplements at higher flows. This segmentation ensures that spray stability and atomization quality are maintained across the entire flow range, with each nozzle operating in its optimal regime.
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 configuration increases the fuel flow range and maintains spray stability and atomization quality across varying conditions, while reducing susceptibility to coking, thereby optimizing combustion efficiency and emissions control in gas turbine engines.
Implementation Method 1
The ABS injector uses a combination of fuel pressure drop and airblast effect for both pre-filming and atomizing the fuel
Implementation Method 2
a primary air jet positioned between the primary fuel injector and the secondary fuel injector to direct a portion of an incoming air stream between the primary air stream and the secondary air stream
Implementation Method 3
for both pre-filming and atomizing the fuel
Implementation Method 4
includes a heat shield to minimize coking risks
Implementation Method 5
Air pollution concerns worldwide have led to stricter emissions standards both domestically and internationally
Data Source
AI summary
A mixer assembly for a gas turbine engine, including: a primary fuel injector having a central axis for injecting a primary fuel spray into a primary air stream, wherein fuel is provided at a desired rate and droplets of the fuel spray are within a desired size range; a secondary fuel injector positioned radially outwardly of the primary fuel injector for injecting a secondary fuel spray into a secondary air stream spaced radially outwardly of and surrounding the primary air stream; and, a primary air jet positioned between the primary fuel injector and the secondary fuel injector to direct a portion of an incoming air stream between the primary air stream and the secondary air stream.