Influence of Hot Flow Conditions on Nozzle Performances

A numerical study on the characteristics of hot flows in a Thrust Optimized Parabolic (TOP) nozzle is conducted. the effects of high temperature on the nozzle performance will be investigated for the Vulcain nozzle in over-expanded conditions. Particular attention is given to the Restricted Shock Separation (RSS) condition, in which recirculation and supersonic annular jets inside the nozzle can be observed. The influence of temperature and gas composition are accounted for through their effect on the thermophysical properties of the mixture, and finally through fully unsteady simulations of a chemically reacting mixture. The obtained results highlight the importance of the modeling approach for the prediction of the separation point. The value of the thrust coefficient has non-negligible variations when considering the least and most accurate models, however it may not be needed to employ a combustion model in order to obtain sufficiently accurate predictions of the thrust coefficient.