PLIF imaging measurements of a co-axial rocket injector spray at elevated pressure

A small-scale rocket combustion chamber has been developed for fundamental investigations on liquid oxygen/gaseous hydrogen (LOX/GH(2)) combustion under high-pressure conditions. The combustion chamber is designed for pressures up to 2 MPa equipped with a unielement shear co-axial injector. The intention of the experimental work is to apply optical diagnostic techniques to show their feasibility in two-phase high-pressure flows and to characterize the phenomenology of the LOX/GH(2) spray flamelike liquid oxygen injection, atomization, evaporation, turbulent mixing, and combustion. Planar laser-induced predissociation fluorescence (PLIPF) and spontaneous emission of OH have been applied at three different chamber pressures in the near field of a shear co-axial injector in the optically accessible rocket chamber. Single shot and averaged images have been measured to map the flame zone, delivering qualitative information of the reactive flow field. Additionally, dispersed fluorescence spectra of OH in the wavelength range of the A (2)Sigma (upsilon' = 3) <-- X (II)-I-2 (upsilon" = 2) fluorescence band have been measured to evaluate interferential effects arising from O-2 that occur with increasing chamber pressures.