Observation of nitric oxide and soot in turbulent diffusion flames and diesel combustion by laser diagnostics.

摘要

Combustion applications such as Diesel engines, boilers and gas turbines are primary sources of NO and NO{dollar}sb2{dollar} emissions. NO and NO{dollar}sb2{dollar} are major atmospheric pollutants which contribute to urban photosmog, acid rain, formation of low altitude ozone and destruction of the stratospheric ozone layer. The desire to solve these problems and emission regulations imposed by the United States Congress and implemented by the Environmental Protection Agency have resulted in an increased effort to understand NO formation and its interaction with soot, another major pollutant. This study aims to develop an in-situ measurement method which can be used to characterize NO and soot evolution in turbulent diffusion flames and, particularly, in Diesel combustion. The technique involves qualitative planar imaging of NO by laser induced fluorescence and soot by Mie scattering and laser induced incandescence. Initially, the technique was tested by acquiring simultaneous planar images of NO and soot in turbulent diffusion flames, which helped to understand the limitations of the experimental equipment. Later, planar images of soot and NO were acquired separately from an optically accessible Diesel engine under conditions that were chosen for optimum laser induced fluorescence measurements. In addition, one-dimensional, semi-quantitative laser induced fluorescence measurements were made to determine NO distributions in hydrocarbon turbulent diffusion flames. Results obtained from these experiments provide information about NO and soot distribution in Diesel combustion and hydrocarbon flames. In the future, the technique developed in this study will be used to characterize NO and soot evolution in Diesel combustion by acquiring simultaneous images of the two species.