Improvement of the SERN nozzle performence by aerodynamic flap design ( Verbesserung der Leistung einer SERN-Düse durch aerodynamische Gestaltung der Düsenklappe

Abstract

As continuation of the former study [P. Gruhn et al., Aerospace Science and Technology 4 (2000) 555-565[, we examine the flow at a SERN nozzle for a future hypersonic cruise vehicle with help of a nozzle/afterbody wind tunnel model. Main focus is on the flow at the nozzle flap and the separation of the boundary layer at the flap cowl. The location of this separation is determined for different nozzle/afterbody model is established. Based on the experiments and recent studies, a geoemtry for the nozzle flap of the ference configuration ELAC of the Collaborative Research Center 253 of the Aachen University of Technology is suggested. Numerical studies result in an improved axial thrust going along with an improved thrust vector angle for this new flap in the whole examined Mach range between 1.23 and 7. The improvements of up to 11 percent in axial thrust coefficient and up to 15° in thrust vector angle at low Mach numbers exceed the progresses made for the nozzle of the nozzle/afterbody model in the former study.