Characterisation of acoustically coupled flow field dynamics from high-speed imaging in a high pressure rocket thrust chamber

In order to investigate the combustion characteristics in a liquid rocket engine, especially on the combustion instability, imaging analyses have been used in high pressure rocket combustion to date. The experiment was conducted with liquid oxygen (LOX) and H2 propellants with 42 shear-coaxial injectors. The chamber has an optical access window through which blue and OH* radiations were captured by high-speed camera with a 436±5 nm filter and a 310nm. In blue radiation images, the LOX jet can be observed and the jet structures were tracked as seeding particles by image correlation velocimetry (ICV) based on particle image velocimetry method (PIV). Therefore, discretized axial and radial velocities were obtained and they were analysed with OH* radiation image by multi-variable dynamic mode decomposition (MDMD).