In the investigation on the prediction of combustion characteristics within a furnace, the combustion model has not been developed adequately because the following aspects are tangled in the spray combustion process; 1) turbulent air and spray flows, 2) atomizing characteristics, 3) heat and mass transfer and 4) combustion. This paper proposed the practical combustion model which can be satisfactory to various combustion conditions.
Previous to combustion simulation, liquid fuel sprays characteristics, whose atomizing principle is based on a pneumatic nozzle with a swirling flow, (radial distribution of air velocity, dispersion, particle diameter) are measured. A computation method of the flow field with the swirling flow is carried out by SIMPLE method where a turbulence flow model (k-ε two-equation model) is used.
A simple reaction model is included in the above turbulence equations from the points of application of the prediction whose model is made that the one-step reaction occurs between fuel vapor and oxygen with an infinite reaction rate. And NOx production rate is computed on the extended Zeldovich mechanism. The combustion characteristics are measured by these modelings using the differential method.
Kerosene spray is fired under the excess air ratio of 1.2 distributions of gas temperature and of gas composition (O2 and NOx) are measured.
The calculated gas temperature and composition within the furnace agree qualitatively with these experimental values. The simulation based on the model can be applied a variety of combustion conditions such as furnace type and kinds of fuel.
