ABSTRACT
The earlier chapters dealt with combustion in a quiescent atmosphere and laminar-flow systems. There the transport properties provide a basic understanding of combustion and essential parameters governing combustion behavior, particularly at the molecular level. In the examination of laminar flows, several assumptions and approximations are made that greatly reduce the complexity of the solution and yield very simple general solutions. However, most practical systems deal with combustion under turbulent conditions, in which an aggregate mass consisting of a large number of molecules is randomly transported just as molecules are randomly transported. For example, the aggregate transfer of momentum (rather than molecules themselves being transported across) results in rapid transfer of momentum compared to molecular transport. If “turbulent” viscosity, which is not a property, has its value defined, it is much larger than molecular viscosity. Hence, transport of momentum species and energy are affected by turbulence. Turbulence plays a major role in pollutant formation and destruction. The combustion process in most practical devices, such as jet engines and industrial power plants, involves turbulence. However, turbulent flows do not lend themselves easily to analysis.
