The Hyperfine Structure of the OH* Emission Spectrum and its Benefits for Combustion Analysis

Kurzfassung

The hyperfine structure of the OH radical emission spectrum was used to derive hydrogen flame temperatures in a research rocket combustor. A spectral resolution of less than 1nm was realized, revealing single molecular emission lines. Hence, relative intensities of several emission lines in the ultraviolet regime were investigated regarding temperature. Two groups of lines were used in order to correlate values of heat release with band intensities. Using an optically accessible diagnostic element, optical fiber, and a high-resolution spectrograph, measurements were conducted during LOX/gH2 combustion runs at the European research test bench P8. The feasibility of line-of-sight flame temperature measurements in the vicinity of the injector element was shown. Temperature values of (3200±200)K were determined. Experimentally obtained values are in good agreement with simulation data.