Numerical approach of a hybrid rocket engine behaviour : Modelling the liquid oxidizer injection using a Lagrangian solver

Abstract: To access and operate in space, a wide range of propulsion systems has been developed, from high-thrust chemical propulsion to low-thrust electrical propulsion, and new kind of systems are considered, such as solar sails and nuclear propulsion. Recently, interest in hybrid rocket engines has been renewed due to their attractive features (safe, cheap, flexible) and they are now investigated and developed by research laboratories such as ONERA.This master’s thesis work is in line with their development at ONERA and aims at finding a methodology to study numerically the liquid oxidizer injection using a Lagrangian solver for the liquid phase. For this reason, it first introduces a model for liquid atomiser developed for aeronautical applications, the FIMUR model, and then focuses on its application to a hybrid rocket engine configuration.The FIMUR model and the Sparte solver have proven to work fine with high mass flow rates on coarse grids. The rocket engine simulations have pointed out the need of an initialisation of the flow field. The methodology study has proven that starting with a reduced liquid mass flow rate is preferable to a simulation with a reduced relaxation between the coupled solvers. The former could not be brought to conclusion due to lack of time but gives an encouraging path to further investigate.