ABSTRACT
Combustion systems are among the most challenging technologies to study. There are not only high temperatures, but usually very high temperature gradients ranging from the incoming reactants at ambient temperature up to ame temperatures. The uid ow is typically turbulent and may include swirl. The heat transfer includes conduction, convection, and radiation. The radiation is further complicated by the spectral nature of gaseous combustion products. The chemistry is extremely complicated, where the combustion of a relatively simple fuel like methane can involve hundreds of chemical reactions and dozens of species. Trace combustion products such as carbon monoxide and nitrogen oxides are critical because they are typically regulated. For liquid and solid fuels, multiple phases are present. The fuel composition can vary widely and may contain multiple components, waste products, and sometimes multiple phases, depending on the process. The length scales in industrial combustion processes may vary by orders of magnitude, ranging from millimeters for fuel injection ports up to meters for the combustor itself. The combustion system may also include heat recuperation equipment such as air preheaters and waste heat boilers, and pollution control equipment such as scrubbers and catalytic treatment reactors. The materials being heated may be solids, liquids, or gases and have a wide range of properties. For example, molten aluminum can be highly reective, molten glass is spectrally absorptive, and cement is highly absorptive.
