Viscous and Inviscid Vortex Generation During Startup of Rocket Nozzles

Abstract

An advanced numerical technique, based on the fitting and tracking of shocks, has been implemented to the simulation of flow transients during startup of axisymmetric rocket nozzles. The results show the occurrence of very peculiar flowfield configurations, not clearly in evidence in the current literature. In particular, two main vortical regions of different nature take place: The first has viscous origin, whereas the second is generated by typically inviscid phenomena. The evolution of these vortices and the interaction with each other and, possibly, with shocks plays an important role in the generation of pressure fluctuations on the nozzle wall and may yield nozzle side loads