Direct Injection Multipoint Nozzle for Turbine Combustion
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Solution Overview
Problem
Turbine engine injectors face challenges in preventing local hot spots that lead to high NOx emissions and maintaining stable flames without autoignition and flashback, due to inadequate mixing of fuel and air.
Innovation Solution
The design incorporates a spray cup with radial and axial air passages and a pressure swirl atomizer that directs fluid and air axially into the combustion chamber, preventing recirculation zones and enhancing atomization and combustion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel is injected directly into the combustion chamber without adequate mixing structures, then the injection system is simple, but local hot spots form leading to high NOx emissions
Solution Approach 1:
The injector is divided into multiple injector modules, each with separate fuel and air passages. The air passages are segmented into radial and axial components that deliver air to different regions of the spray cup chamber, enabling controlled segmentation of the mixing process to prevent local hot spots.
Solution Approach 2:
Different regions of the spray cup chamber receive air from different directions (radial vs. axial passages) to create locally optimized mixing conditions. The radial air passages provide air at the periphery while axial passages provide air along the centerline, creating spatially varying quality of mixing to prevent hot spots.
2Object-generated harmful factors
If air flow is increased to improve mixing and reduce hot spots, then NOx emissions decrease, but flame stability may be compromised leading to autoignition or flashback
Solution Approach 1:
The air supply is segmented into radial and axial passages that deliver air to different zones of the chamber. This segmentation allows the air flow to be distributed in a manner that promotes mixing without creating high-velocity jets that could destabilize the flame or cause flashback.
Solution Approach 2:
Air is introduced from multiple dimensions (radial direction from cup walls and axial direction from the atomizer) rather than a single direction. This multi-dimensional air introduction creates more uniform mixing while maintaining flame stability by avoiding concentrated high-velocity flow paths.
3Quantity of substance
If recirculation zones are allowed to form at the base of the spray cup, then fuel-air mixing may be enhanced, but unstable combustion and flashback can occur
Solution Approach 1:
Instead of allowing recirculation zones to form at the base of the spray cup (which can cause instability), the design inverts the approach by introducing air axially from the atomizer upward through the chamber. This upward axial flow counteracts the tendency for recirculation and prevents flashback while still achieving thorough mixing.
Solution Approach 2:
Air is introduced axially from the atomizer before fuel reaches certain regions of the chamber, pre-positioning oxidizer in locations where it can mix with fuel without creating recirculation zones. This preliminary air placement ensures stable combustion by preventing fuel accumulation that could lead to flashback.
4Productivity
If the injector modules are positioned close to the combustion chamber to improve atomization, then combustion efficiency increases, but the injector modules are exposed to high combustion heat
Solution Approach 1:
The spray cup acts as an intermediary structure between the injector modules and the combustion chamber. It provides a chamber where fuel and air can mix before entering the high-temperature combustion zone, allowing the injector modules to remain slightly removed from the hottest regions while still achieving efficient combustion through the mixing chamber geometry.
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 improves atomization, maintains stable flames, and reduces NOx emissions by ensuring thorough mixing of fuel and air, preventing local hot spots and autoignition, while also protecting the injector modules from combustion heat.
Implementation Method 1
a pressure swirl atomizer attached to the spray cup and having a fluid passage for directing fluid axially into chamber
Implementation Method 2
a plurality of radial air passages extending through the spray cup for directing air radially inwardly into the chamber
Implementation Method 3
a heatshield assembled to a downstream end of each injector module, the heatshield including a body for protecting the injector modules from combustion heat
Data Source
AI summary
Provided is an injector (30) having a plurality of injector modules (44) that include a spray cup having a chamber and a plurality of radial air passages for directing air radially into the chamber, and a pressure swirl atomizer attached to the spray cup and having a fluid passage for directing fluid axially into chamber and an air passage for directing air axially into the chamber. By providing radial and axial air flow and axial fuel flow into the chamber, the fuel may be mixed to prevent local hot spots that lead to high NOx emissions, and a stable flame may be maintained without autoignition and flashback. The axial air flow also prevents recirculation zones from forming at a base of the spray cup, provides improved atomization and enhanced combustion.