ABSTRACT
Temperature is one of the key quantities in combustion research, where it governs the overall efficiency of the combustion process. Most of the che mical reactions in a flame, which are responsible for the heat release or the formation of pollutants, are strongly dependent on temperature. In addi tion, thermal stress on the mechanical structure of the combustion devices determines the applicability of materials, lifetime, and reliability. A funda mental understanding of these processes requires accurate and reliable infor mation on temperature. This chapter describes several state-of-the-art laserspectroscopic techniques, which have been used successfully for temperature measurement in combustion. Because there is no single laser diagnostic technique that can be applied under all circumstances, the particular appli cation must be carefully considered. Pointwise measurements certainly yield the best accuracy. Imaging methods for 1-D and 2-D temperature determi nation may be employed to study temperature gradients or temperature fields but may lead to reduced absolute accuracy. The specific properties of the commonly used laser-spectroscopic techniques, together with their limitations, will be discussed in the following sections. This chapter, how ever, cannot review the fundamentals of laser-based thermometry in depth. Here we refer to comprehensive review articles [1,2]. We will restrict our selves to the citation of more recent publications, and the selected examples in Section 6.4 are the results of some experiments that have been performed in the laboratories at the German Aerospace Center (DLR) and represent the experience gained from this work.
