Prediction of Flow Separation and Side-loads in Rocket Nozzle Using Large-eddy Simulation

Abstract

The design process is a critical issue in order to improve rocket engine performance. Indeed, the prediction of the aerodynamic forces acting on the nozzle, in particular the off-axis loads, is challenging even for modern methods. In this study, the flow of an exit Mach number Truncated Ideal Contour (TIC) nozzle is numerically investigated by means of Large-Eddy Simulation (LES), using the unstructured compressible AVBP solver developed by CERFACS. The study focuses on an over-expanded regime characterised by a Free-Shock Separation (FSS). To obtain an accurate prediction of the flow, an Adaptive Mesh Refinement (AMR) methodology is used. Results show that wall-modelled LES combined with AMR allows to accurately capture the jet flow dynamics while at the same time reducing the CPU time of LES: both the location of the mean separation point along with the pressure fluctuations inside the nozzle are well captured. In particular, the two peaks of the pressure Power Spectral Density contributing to the side-loads mechanism are correctly predicted compared to experiment.