Methodology to solve flowfields of plug nozzles for future launchers

In the development of future launchers, in particular the single stage to orbit launcher, the use of plug nozzles looks promising because of the possibility of improving performance; therefore the capability to achieve accurate evaluations of the relevant flowfields is required. Nevertheless, because of typical flow features, analyses performed by the common computational fluid dynamics methods lead to uncertain and time-consuming results, To circumvent some of these problems an approach based on a simple simulation model that replaces the mixing layer between the nozzle jet and external flow by a contact discontinuity was recently proposed by the authors. Following this approach the complex calculation of the turbulent mixing of flows having different thermodynamic characteristics can be avoided, while correctly accounting for the main features of the flowfield. In this paper this simple model was implemented to compute linear plug nozzle flowfields at different ambient conditions and for different geometries of the plug. The expected flow behavior has been well reproduced and good agreement with the theoretical nozzle performance has been achieved, allowing a performance analysis for some of the main characteristic parameters to be carried out.