Cryogenic propellant combustion is investigated in this paper. It is shown that the mean flame structure may be obtained by applying computerized tomography principles to oxygen-hydrogen (OH) emission images obtained from experiments on a shear coaxial injector. The data correspond to injection conditions typical of those found in rocket motors, but to lower operating pressures of 1, 5, and 10 bar. The transformed emission images yield the mean volumetric OH emission distribution. This quantity may be roughly interpreted as the mean volumetric rate of reaction. The data provide the location of the mean flame zone and confirm that stabilization takes place in the immediate vicinity of the injection plane.
This paper reports results from experiments carried out on the jet name formed from a single coaxial injector. This device was fed with Liquid oxygen and gaseous hydrogen and placed in a chamber equipped with quartz windows. The flame is observed with a set of optical methods: light emission from OH radicals, laser-induced fluorescence of OH and O-2, elastic, and Raman scattering from the liquid-oxygen jet. These techniques are used to obtain images of the name zone. It is then possible to deduce the name location with respect to the liquid jet from simultaneous elastic scattering and laser-induced fluorescence of OH measurements. Average emission images treated with Abel's transform provide the local volumetric light emission from OH radicals, This yields the mean flame structure and constitutes a different method for locating the flame. The images obtained by exciting the fluorescence of O-2 provide complementary information on the flame shape and they may be used to estimate the local reaction rate. Quantitative temperature measurements based on coherent anti-Stokes Raman scattering from H-2 give additional dues on the combustion zone. These data may be used to develop a unified picture of the name in the vicinity of the injection plane.