Full-length visualisation of liquid oxygen disintegration in a single injector sub-scale rocket combustor

Abstract

This work presents results of an effort to create an extended experimental database for the validation of numerical tools for high pressure oxygen-hydrogen rocket combustion. A sub-scale thrust chamber has been operated at nine load points covering both sub- and supercritical chamber pressures with respect to the thermodynamic critical pressure of oxygen. Liquid oxygen and gaseous hydrogen were injected through a single, shear coaxial injector element at temperatures of around 120 K and 130 K, respectively. High-speed optical diagnostics were implemented to visualise the flow field along the full length of the combustion chamber. This work presents the analysis of shadowgraph imaging for characterising the disintegration of the liquid oxygen jet. The large imaging data sets are reduced to polynomial profiles of shadowgraph intensity which are intended to provide a more direct means of comparison with similarly reduced numerical results. Comparing half-lengths of these profiles across operating conditions show clear groupings of load points by combustion chamber pressure and mixture ratio. All load points appear to collapse to an inverse dependence of length on impulse flux ratio.