Sur l'usage d'une approche ZDES bi-espèce pour l'étude des configurations de lanceurs spatiaux multi-tuyères

International audience; In order to study the unsteady flows occurring in the wake of space launchers, numerical models have to provide an accurate description of both the turbulent behaviour of base flows and the thermodynamic properties of the multi-species and reactive propulsive jets. As the complexity of models dedicated to each of these objectives can have a significant impact on computational cost, especially for reusable designs including several nozzles, authors have often to establish a compromise between an accurate treatment of turbulence and the taking into account of chemistry effects. To contribute to the improvement of launcher base flow predictions, this paper presents the study of a four-nozzle space launcher configuration with a dedicated numerical workflow focusing on the treatment of turbulence. Indeed, such a case has only been studied with RANS approaches so far, and is treated here with the automatic mode of the Zonal Detached Eddy Simulation (ZDES Mode 2 2020) and hybrid numerical methods, based on Ducros' sensor and allowing to resolve well the turbulent fluctuations of the base flow while capturing the strong normal shock structures inside the jets. The computations are furthermore performed thanks to inert bi-species numerical methods enabling to take into account some thermodynamic properties of the jets with an acceptable computational cost. The bi-species scale resolving numerical workflow is able to reproduce the main features of multi-jets afterbody flows and provides a satisfying agreement with experimental pressure measurements. Compared with RANS calculations, the use of ZDES not only gives access to additional information regarding the unsteadiness of the flow but also provides distinct predictions of the mean aerodynamic field.