Simulation of Electrical Characteristics in Oxyfuel Flame Subject to An Electric Field

The oxyfuel cutting method is still widely used nowadays, even though it is not a fully autonomous process. Thisthesis presents a computational model to study ion and electron transport and current-voltage characteristics inside a methane-oxygen flame. By finding the relationship between current-voltage characteristics and critical parameters,such as standoff, fuel oxygen ratio, and flow rate, a control algorithm could be implemented into the system and make it autonomous. Star CCM+ software is used to develop preheat phase computational models by splitting the simulations into the combustion and electrochemical transport parts. Both the laminar and turbulent flows are considered. Several laboratory experiments are used to compare test data with the numerical results generated using this model. The initial and boundary conditions used in the simulation were to the extent possible similar to the experimental conditions in the laboratory experiment.

In the combustion part, the general GRI3.0 mechanism plus three additional ionization reactions are applied, and the combustion part results are then used as input into the electrochemical transport part. A particular inspection line inside the domain is created to analyze the results of the electrochemical transport part. Ions, electrons number density, and current density are studied in the interval from -40V to 40V electric potential. The ions are heavier and more challenging to move than electrons. The results show that at both the torch and work surfaces, charged sheaths are formed, which cause three different regions of current-voltage relations to form in a similar manner as observed in the tests.