Temperature and H2O concentration detection in axisymmetric combustion spaces using spontaneous emission and absorption combined signals

Abstract

Combustion temperature and gas concentration are important parameters for understanding combustion status. Two types of signals including spontaneous emission and absorption signals are usually used for combustion temperature and gas concentration measurement. In this work, a combined method utilizing both spontaneous emission and absorption signals is proposed for combustion detection. The integrated spectral band ratio (ISBR) method based on spontaneous emission signals is first applied to reconstruct the temperature field. Then, with the known combustion temperature, the absorption tomography (AT) method using absorption signals is employed to reconstruct the gas concentration field. Several factors including absorption path layout and number, scanning band number, which influence the accuracy of the combined method are investigated and optimized. Then, the combined method is applied to reconstruct two-dimensional temperature and gas concentration fields of axisymmetric combustion spaces. Results show that the combined method retains the advantage of the ISBR method with high accuracy of temperature measurement, while significantly improving gas concentration measurement accuracy compared to the ISBR method. Additionally, the combined method offers clear advantages over the AT method in terms of simpler apparatus.