Combustion Of Chemical Components In The Field Of Optical Computerized Tomography Temperature Reconstruction

Optical Computerized Tomography (OCT) is a branch of Computerized Tomography. It is a kind of measurement technique which is famous for real-time, stable and non-contact et al characteristics. In principle, all the OCT methods only can obtain the refractive index distribution for the measured flow fields. However, up to now, the components of the measured flow field are mostly supposed, when reconstructing the density and temperature distributions. In this paper, the effect of flow fields'chemical components on reconstructing temperature distribution is studied. The main work can be concluded as follows:Firstly, the relation between the refractive index and the measured parameters is discussed in detail, based on depicting the basic knowledge of flow fields'OCT diagnosis.Taking the combustion of hydrocarbon in air for example, equilibrium constant method is introduced to obtain the chemical components of the flame. As a result, the dependence of the chemical components'mole fraction on temperature and pressure is established, on the condition of oxygen-rich or poor and complete combustion situations respectively. The comparative results indicate that components have important effect on flow fields'refractive index in the given temperature and pressure ranges, which will have effect on flow fields' temperature reconstruction precision.In order to verify the effect of component on flow field's temperature reconstruction by OCT methods, the experimental apparatus of moire deflection tomography is built while the propane-air flame is chosen as a practical example for experiment. The temperature distributions which derive from the same refractive index but with different components are compared. It is found that the maximal temperature difference is nearly 100K between the two different suppositions on components. In particular, the temperature which is based on the model of considering the real components of flame flow field matches well with that of the reported experimental result by thermocouple. Hence, it is proved by experiment that the effect of specific composition on temperature reconstruction by OCT methods can not be omitted.In short, this dissertation will be benefit to improve the precision of temperature reconstruction for flow fields which are diagnosed by the OCT methods.