CARS Investigation of a Hydrogen-Oxygen High-Pressure Pulsed Burner

Kurzfassung

During recent years the methods of CARS spectroscopy have been applied to the studies of hydrogen-air and hydrogen-oxygen combustion processes. For accomplishment of spectroscopic gas temperature measurements usually CARS spectra of Q-branches of hydrogen are used in this case [1,2]. Under the real conditions characterized by high pressures of 10 – 100 atmospheres and high temperatures of 2000 – 3000 K registration of CARS spectra should be accomplishes by knowledge of broadening and shift of the Q-branch lines, mainly perturbed by collisions with water molecules. Previous cell experiments conducted up to 900 K in a binary H2-H2O mixture show that for the hydrogen Q-branch lines there exists significant broadening and its dependence on temperature and rotational quantum number [3,4]. In order to obtain line-broadening data for higher temperatures and densities we propose to use a high pressure pulsed H2-O2 burner. The combustion chamber of the burner we used is filled during 30 msec with the help of pulsed valves by a H2/O2 mixture that is later ignited by a spark plug. Combustion products flow into open air through a small slit in the burner walls. Two CARS spectrometers are simultaneously used to probe combustion products in a jet at a distance X/D=1. One of them is tuned to selected hydrogen Q-branch rotational component with further investigation of the width and shift of the CARS line by a Fabry-Perot interferometer. Another spectrometer detects water and hydrogen spectra for density and temperature evaluation. In the present work preliminary results on characterization of our pulsed high pressure burner and some measurements of broadening and shift of the Q-branch lines of hydrogen in combustion products of the pulsed burner are given.