Flow separation in out-of-round nozzles, a numerical and experimental study

¹ German Aerospace Center (DLR), Institute for Space Propulsion Lampoldshausen 74239, Germany
² German Aerospace Center (DLR) Institute of Aerodynamics and Flow Technology Braunschweig 38108, Germany

Abstract

The start-up and shutdown transient phases in rocket engine nozzles generate high side loads. The internal and external flow fluctuations can excite the eigenmodes of the nozzle structure. The flow separation in out-of-round nozzle intensifies the initial structure deformation leading in the worst case to the collapse of the nozzle. In the framework of the DLR internal cooperation program ProTAU, the ovalization of nozzles is being investigated from both the numerical and the experimental point of view. Three nozzle geometries have been designed and deformed applying various methods. The flow behavior in the initially axisymmetric and the ovalized contours has been numerically investigated. The most promising contours will be manufactured as permanently ovalized nozzle models and tested under cold flow conditions.