Presentation on theme: "Phenomenological Model for Hydrocarbon High-Temperature Autoignition M. Petrova & F. Williams Domenic Tassoni."— Presentation transcript:
Phenomenological Model for Hydrocarbon High-Temperature Autoignition M. Petrova & F. Williams Domenic Tassoni
Combustion Model Hydrocarbons above 1000 K Four step chain process – Fuel/Oxidizer Collision – Fuel Consumption by free radicals – Oxidizer Consumption by free radicals – Chain Termination
Role of Radicals in Combustion Combustion of hydrocarbons releases energy. This energy causes stable molecules to dissociate into reactive radicals OH, H, O are all common radicals These radicals cause more reactions which raises the temperature further.
Allene (C 3 H 4 ) Example Initiation Step: C 3 H 4 + O 2 → C 3 H 3 + HO 2 Small concentrations of H also generated. Fuel Consumption Step: H + C 3 H 4 → CH 3 + C 2 H 2 Radical concentration decreases.
Allene (C 3 H 4 ) Example Cont. Oxidizer Consumption Step: H + O 2 → OH + O Radical concentration increases. Termination Step: 2O → O 2 or similar Responsible for primary heat release.
Relevance Radical depletion rates can be used to determine autoignition times. Where k i is the reaction-rate of a step. Also, α and β are condition specific parameters related to radical generation.
Other Possible Uses for the Model Burning velocities Diffusion-flame extinction conditions Detonation cell sizes