Oblique Injection Nozzle for Gas Turbine Combustor Heat Blocking
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Solution Overview
Problem
The combustor section of gas turbines experiences self-ignition and flashback phenomena due to unblocked flame and radiant heat from the combustion chamber affecting the injection nozzle where fuel and compressed air are mixed.
Innovation Solution
An injection nozzle with an obliquely connected intermediate portion between the inlet and outlet portions, featuring a prismatic shape with increasing inner width downstream and curved surfaces to deflect radiant heat back into the combustion chamber, preventing autoignition and flashback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a straight tube-type injection nozzle is used, then the structure is simple and easy to manufacture, but radiant heat and flame from the combustion chamber are not blocked and are transmitted to the fuel-air mixture area causing self-ignition and flashback
Solution Approach 1:
The injection nozzle is divided into multiple sections: an inlet portion, an intermediate portion with oblique inner walls, and an outlet portion. This segmentation creates a barrier structure that blocks radiant heat and flame from reaching the fuel-air mixture area while maintaining manufacturing feasibility through modular design
Solution Approach 2:
The intermediate portion with oblique inner walls acts as an intermediary barrier between the combustion chamber and the fuel-air mixture area. This intermediate structure reflects radiant heat back into the combustion chamber, preventing heat transmission to the mixture area and eliminating self-ignition and flashback risks
2Reliability
If the intermediate portion has oblique inner walls, then radiant heat is reflected back into the combustion chamber preventing self-ignition, but the manufacturing complexity increases
Solution Approach 1:
The oblique inner walls are implemented only in the intermediate portion where heat blocking is most critical, while the inlet and outlet portions maintain simpler geometries. This localized application of complexity achieves the necessary heat reflection function without unnecessarily complicating the entire nozzle structure
Solution Approach 2:
The intermediate portion features asymmetric oblique inner walls with specific angles designed to optimize heat reflection. This asymmetric geometry is tailored to the specific thermal flow patterns in the combustion chamber, providing effective heat blocking with minimal structural complexity
3Reliability
If the inner width of the intermediate portion increases downstream, then fluid flow is stabilized and radiant heat reflection is improved, but the nozzle occupies more space
Solution Approach 1:
The inner width of the intermediate portion varies dynamically along the downstream direction, increasing gradually to optimize fluid flow stability and heat reflection. This dynamic geometry adaptation allows the nozzle to achieve superior performance within a compact volume by optimizing the flow path progressively rather than maintaining a constant large cross-section
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
Effectively prevents the transfer of radiant heat and flame to the fuel-air mixture area, stabilizes fluid flow, and prevents autoignition and flashback occurrences in gas turbines.
Implementation Method 1
curved surfaces to deflect radiant heat back into the combustion chamber
Data Source
AI summary
An injection nozzle installed in a combustor of a gas turbine to inject fuel and compressed air into a combustion chamber is provided. The injection nozzle includes an inlet portion into which fuel and compressed air are introduced, an outlet portion disposed downstream of the inlet portion in a flow direction of fluid and configured to discharge the fuel and compressed air to the combustion chamber, and an intermediate portion disposed between the inlet portion and the outlet portion and connected obliquely to each of the inlet portion and outlet portion, wherein each of the inlet portion, the outlet portion, and the intermediate portion has a prismatic shape.