Characterization of the Primary Ignition Process of a Coaxial GH2/LOX Spray

Abstract

The ignition transient of a cryogenic GH2/LOX spray has been investigated for a range of injection conditions as characterized by Re- and We-numbers as well as momentum flux ratios. The temporal evolution of the flow and the flame after ignition by a laser induced gas breakdown has been recorded by high-speed visualization techniques. For the early times of the ignition transient from these data convection and flame front velocities are deduced by image processing techniques. The parameters controlling the flame and flow evolution are discussed based on the variation of the ignition transient with the injection conditions. In addition to the experiments numerical simulations are used to analyze the cold flow prior to ignition in order to get insight into flow characteristics at the time of ignition. From these calculations mean velocities in the GH 2 shear layer have been extracted and compared to the convection velocity deduced from the experiments.