Cfd simulation of a 1kn paraffin-fueled hybrid rocket engine

Hybrid rocket engines (HREs) are rocket engines that combine a solid fuel and a liquid (or gaseous) oxidizer, or vice versa. A setup with a solid fuel is most commonly used. For some years now, researchers at Université Libre de Bruxelles (ULB) are running tests with a test bench HRE. This engine has a target thrust of 1 kN and uses a paraffin fuel with liquid N₂O as oxidizer. A first computational fluid dynamics (CFD) simulation of this engine is presented here. It is a steady-state RANS simulation, using the standard k-∈turbulence model together with the Eddy Dissipation Model (EDM) for the turbulence chemistry interaction (TCI). Oxidizer and fuel enter the domain in a gaseous phase. An ambient area is included in the computational domain as well. This avoids imposing a boundary condition at the nozzle exit section, and therefore a more correct pressure profile can be formed. Furthermore, it allows to compare and investigate the exhaust plume structure. The results are compared with test firing data and show an average deviation of less than 10%. Also, a parametric study is done regarding the oxidizer and fuel inlet temperatures and the oxidizer to fuel mass ratio (O/F ratio). Using the CFD model, future work will aim on improving the engine’s performance by focusing on the design influence of the post combustion chamber and nozzle.