Schlieren Imaging of the Combustion of Classical and High Regression Rate Hybrid Rocket Fuels

This paper explores turbulent boundary layer development within a hybrid rocket motor. Schlieren images of the combustion of typical hybrid motor fuels with gaseous oxygen in a slab-burning configuration are presented. The recently upgraded Stanford Combustion Visualization Facility was used to conduct atmospheric pressure tests investigating the combustion of classical fuels such as Hydroxyl-Terminated PolyButadiene (HTPB), High Density PolyEtheylene (HDPE) and polymethyl methacrylate (PMMA) as well as liquefying high regression rate fuels, specifically neat paraffin with blackener. High speed color and schlieren videos were recorded for each test. No drastic change in boundary thickness growth was observed for the different fuels in the range of mass fluxes studied.