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.
A Reynolds-averaged Navier-Stokes solver is suitably set up to predict the flow field within paraffin-based hybrid rocket thrust chambers. The regression rate is modeled through a gas/surface interaction boundary condition based on wall mass and energy balances. In particular, the radiative heat flux contribution is included into the energy balance after being computed via discrete transfer method along the whole thrust chamber. The combustion process is modeled via finite-rate chemistry employing global reaction mechanisms. In particular, a thermal cracking reaction step for paraffin-wax is included into the mechanism. Moreover, the liquefied paraffin-wax is treated as a dense fluid because in the supercritical pressure regime. An experimental test campaign on a lab-scale gaseous oxygen/paraffin-wax hybrid rocket engine is fully simulated with the present computational fluid dynamics model. The main results obtained are presented for different test conditions. Comparisons with experimental data are carried out to identify possible future improvements
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.