Numerical Investigation of Flow Phenomena in a Planar Expansion-Deflection Nozzle

Speaker: Gerrit Stich, University of Stuttgart
December 10, 2015

Presentation

Abstract

Reducing the mass of a launcher's upper stage results directly in a higher payload capability. Long combustion chambers of modern expander cycle engines and large high aspect ratio nozzles enlarge the launcher, thus the structural mass. An expansion-deflection nozzle in reverse flow configuration, so an integrated combustion chamber into the supersonic nozzle shows payload gain compared to classical design. The expansion deflection nozzle design was studied in the 60s and 70s for its altitude compensation potential and it is currently again under consideration at the German Aerospace Center (DLR) Lampoldshausen. The complex flow field in an expansion deflection nozzle, with its trisonic throat flow field, supersonic and recirculating subsonic flow, separation, reattachment and moving shear layers is still a challenge for numerical investigations. Previous simulations have shown a comprehensive impact of inherent uncertainties on global and local flow properties and thereby onto the solution of a problem, ranging from grid generation to choice of turbulence model. Sufficient knowledge about the used tools is of major importance, therefore it is necessary to make use of existing validation methods in order to determine the predictive capability and reliability of a computational model for its intended use.

Biography

Gerrit Stich is a Masters student at the University of Stuttgart in Germany, currently conducting a research project in Stanford University's Aeronautics & Astronautics Department. He worked for the German Aerospace Center (DLR) since 2013 where he conducted several RANS simulations with the DLR Tau Code on flow separation in over-expanded rocket nozzles and in Expansion-Deflection Nozzles. His current work at Stanford focuses on Large-Eddy Simulations of rocket nozzles with higher-order shock-capturing schemes. During his time at the University of Stuttgart, he also worked as a branch manager at Germanys biggest supermarket chain, Lidl. Before he attended the University of Stuttgart, Gerrit also worked as a investment banker for Kreissparkasse Esslingen-Nürtingen in Germany and studied mathematics and physics at the University of Tuebingen in Germany.

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