EXPERIMENTAL AND NUMERICAL STUDIES ON LEAN TURBULENT PREMIXED FLAMES

Date

2023-8-08

Author

Güleryüz, Dilay

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Combustion emissions mitigation requirements and increased energy efficiency demands pose stringent conditions on the design of new combustors. Emission requirements indicate the use of hydrogen (as fuel and energy carrier) as a potential solution. Although hydrogen decreases carbon emissions when substituted with carbon-based fuels, it has many peculiarities, such as higher flame propagation velocities, reduced instantaneous flame thickness, increased flame flashback risks, reduced average flame dimensions, increased flame temperature, and increased NOx emissions potential due to higher flame temperatures. These characteristics justify the detailed investigation of hydrogenated mixtures. Another way to reach efficient and cleaner combustion is to use lean premixed fuels.. However, lean premixed combustion faces the problem of flame instability; therefore, predicting the design points in terms of flame properties is crucial for better combustor designs. The experimental facility we developed permits such investigations. The system comprises a high pressure combustion chamber, a turbulent premixed flame burner. The optical diagnostics used are OH* and CH* chemiluminescence and laser induced Mie Scattering tomography technics. Turbulent lean premixed flames under atmospheric pressure for various hydrogen + natural gas + air mixtures are experimentally and numerically investigated. The main premixed turbulent flame parameters we determined concern the instantaneous and average flame topology (such as the turbulent flame brush thickness, flame height, and flame curvature distributions) from which we deduced global combustion parameters such as the turbulent flame propagation speed. In addition, Large Eddy Simulation computations by employing various calculation methods are performed. The numerical results are compared with the experiments.

Subject Keywords

Combustion, Lean Premixed Turbulent Flames, Hydrogen, Optical Measurement Techniques, CFD

URI

https://hdl.handle.net/11511/104876

Collections

Graduate School of Natural and Applied Sciences, Thesis