Angled Apertures Cool Gas Turbine Diffusion Tips
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Solution Overview
Problem
Existing diffusion tips in gas turbine engines face thermal stresses and mechanical failure due to high temperatures, leading to soot deposits and reduced structural integrity, which increases maintenance costs and requires the use of expensive, thermally resistant materials.
Innovation Solution
The diffusion tip features a plurality of angled apertures that discharge a diffusion flow at specific angles to enhance cooling, prevent soot buildup, and distribute a cooling air film uniformly, thereby reducing thermal gradients and stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling circuits are included in the diffusion tip to reduce temperature, then the temperature of the diffusion tip is reduced, but a fuel rich environment is produced which increases soot deposits on the diffusion tip
Solution Approach 1:
The patent applies local quality by creating different flow conditions at different locations on the diffusion tip. The cooling circuits are strategically positioned to provide localized cooling where thermal stresses are most severe, while the swirler assembly creates a localized fuel-lean environment at the flame zone to prevent soot formation. This spatial differentiation allows temperature reduction without uniformly creating fuel-rich conditions that cause soot deposits.
Solution Approach 2:
The patent changes the flow parameters by introducing a swirler assembly that modifies the airflow characteristics. The swirler creates rotational flow and pressure variations that prevent fuel-rich conditions from forming in the combustion zone, thereby preventing soot deposits while allowing the cooling circuits to effectively reduce diffusion tip temperature.
2Reliability
If special metal alloys resistant to thermal wear are used in combustor components, then thermal wear resistance is improved, but cost and weight of the engine increase
Solution Approach 1:
The patent employs conventional, less expensive metal alloys instead of specialized high-temperature resistant alloys. By implementing effective cooling circuits and optimizing the combustion airflow with the swirler assembly, the patent extends the service life of components made from standard materials, making them functionally equivalent to components made from expensive specialized alloys without the added cost and weight.
Solution Approach 2:
The patent changes the thermal environment parameters around the combustor components through active cooling and airflow management. The cooling circuits maintain lower operating temperatures, and the swirler assembly optimizes combustion efficiency, allowing conventional materials to withstand thermal conditions that would otherwise require specialized high-temperature alloys.
3Temperature
If cooling circuits are included in the diffusion tip, then temperature is reduced, but the structure and flow characteristics are adversely affected by soot deposits
Solution Approach 1:
The patent creates localized fuel-lean conditions in the combustion zone through the swirler assembly, preventing soot formation specifically in areas where soot would adversely affect flow characteristics. This localized control of combustion quality ensures that cooling circuits can reduce temperature without the harmful side effect of soot deposits altering flow patterns.
Solution Approach 2:
The swirler assembly creates a feedback mechanism where rotational airflow continuously supplies oxygen to the combustion zone, preventing fuel-rich conditions that lead to soot formation. This active flow management ensures that cooling operations do not create the fuel-rich environment that would otherwise lead to soot deposits and degraded flow characteristics.
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 cooling efficiency, reduces soot deposits, and allows for the use of less expensive materials, decreasing manufacturing costs and extending the lifespan of combustor components.
Implementation Method 1
The diffusion tip forms a pathway for fuel, air or a combination of both, that works in combination with a main premixing circuit of the fuel nozzle. The integrated fuel and/or air mixture is discharged from the tip for ignition
Implementation Method 2
an exterior surface of the diffusion tip may be exposed to high temperature combustion gases. Continued exposure to the high temperatures may induce thermal stresses in the diffusion tip
Implementation Method 3
At least some known gas turbine engines ignite a fuel-air mixture in a combustor to generate a combustion gas stream
Data Source
AI summary
A method and apparatus for a diffusion tip for use with a fuel nozzle is described. The diffusion tip has a substantially circular body including an outer surface and an opposite inner surface. The diffusion tip body extends from a discharge end to an inlet end. The diffusion tip includes an inlet surface adjacent to the discharge end and defined within the body. A discharge surface is defined opposite the inlet surface. A plurality of diffusion apertures each extend between the discharge surface and the inlet surface, each aperture is oriented relative to the body to discharge a diffusion flow outward therefrom at an angle γ (gamma) measured in an X-Z plane between a centerline of the aperture and an X-axis extending tangentially to the outer surface, and at an angle θ (theta) measured in a Y-Z plane between the centerline of the aperture and a Y-axis extending radially outward from the centerline.