Análise numérica da performance aerodinâmica do motor-foguete S-30 acoplado a um demonstrador scramjet

Abstract

This work investigates the effect of the coupling of a scramjet demonstrator in the Brazilian S-30 rocket engine in terms of a numerical investigation of the flow around its fuselage geometry. Local aspects of the flow and the comparison of global flow parameters, such as the pressure and friction drag, were considered for cases with and without the coupled scramjet demonstrator. The rocket engine with the attached scramjet geometry was selected for operational flight conditions corresponding to a Mach number of 5.79 and an altitude of 20 km. A set of 2D RANS simulations were performed, using the Ansys FLUENT software, to investigate the flow dynamics of both configurations. Experimental data obtained from the literature for the S-30 flight was used to impose the required inlet boundary conditions. In order to obtain the drag curve for the case of the scramjet coupled to the S-30 vehicle, numerical simulations were performed for several points along the trajectory of the rocket engine, e.g., before and after the scramjet operational point. The simulations were able to capture the theoretically expected planar and conical oblique shock and the expansion waves that usually occur for a hypersonic flow in such geometries. For instance, the emergence of recirculation zones and flow instabilities due to the shock-wave boundary-layer interactions. Finally, as a result of the attachment of the scramjet demonstrator to the S-30 rocket engine, the results show an increase in the total drag of about 45.25% in the region of the trajectory where the scramjet becomes fully operational. Based on these simulations, the total drag curve was determined for both geometries. A decrease of the average drag coefficient along the trajectory was observed. Using a simple flight dynamic analysis, the trajectory expected for each case was determined. The comparison between the trajectories for both cases shows a small but nonnegligible deviation of about 2% for the altitude and 0,15% for the flow velocity.