Numerical and Experimental Investigation of Flow Separation in Ovalized Nozzles

During the unsteady start-up and shut-down process in supersonic rocket engine nozzles high sideloads can occur. Fluctuations, e.g. in the propellant feeding mass flow or the ambient pressure, can excite the nozzle’s Eigenmodes leading to deformation and, in the worst case, to destruction of the nozzle structure. Separation of the nozzle flow amplifies this excitation. The flow characteristics in ovalized rocket nozzles and their influence on the nozzle structure is therefore investigated within the framework of the DLR internal cooperation program ProTAU. Three TIC nozzles have been designed, manufactured and tested to provide validation data for numerical simulations. The influence of the used turbulence model on the wall pressure and shock system have been investigated for the undeformed and a set of generically deformed nozzle contours.