edited by: Cameron Tropea, AlexanderL Yarin, JohnF Foss
Combustion processes consist of a complex multidimensional interaction between fluid mechanics and chemical kinetics. A comprehensive experimental analysis needs therefore measurements of flow and scalar fields. These measurements need to be performed in-situ with high temporal and spatial resolution as well as high accuracy and precision. In addition, any disturbances during the measurement should be avoided. These requirements are fulfilled best by laser-optical techniques. Whereas flow fields are commonly measured by methods like laser Doppler or particle imaging velocimetry discussed elsewhere, the focus of this chapter is on scalar measurements based on spectroscopy. Scalars of interest are temperatures, chemical species concentrations, or rate of mixing between fuel and oxidant. Following an introduction, Sect. 20.3 presents the interconnection between experimental analysis and numerical simulation of combustion processes. In Sect. 20.4, various spectroscopic techniques are described exemplary in their application to different fields of combustion research. The chapter concludes with aspects on future developments in combustion diagnostics.