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Proposing Institution

Lehrstuhl für Aerodynamik, TU München
Project Manager

Dr.-Ing. Stefan Hickel
Boltzmannstr. 15
85748 Garching
Laval nozzles (such as rocket engines) consist of a convergent-divergent geometry. By definition, the flow speed inside a Laval nozzle is accelerated from sub- to supersonic conditions. A high backpressure at the outlet can lead to an instantaneous deceleration of the flow within the divergent part of the nozzle. Then a jump discontinuity (shock) appears in the pressure, temperature and density distribution along the nozzle. In contrast to the quasi-1-D inviscid theory, this shock interacts in practice with the turbulent boundary layers at the channel walls and causes flow separation. Flow separation and reattachment is a particularly challenging subject of enduring fluid dynamics research and results in a complex 3 D system of interacting oblique shocks, compression and expansion waves, which is referred to as pseudo-shock system. These pseudo-shock systems influence reliability and performance of a wide range of flow devices, such as ducts and pipelines in the field of process engineering and supersonic aircraft inlets. Thus, the optimization of pseudo-shock systems is of great academic and commercial interest. The purpose of this project is the numerical investigation of a pseudo-shock system. Prior simulations using the common Reynolds averaged Navier-Stokes (RANS) approach showed that the results are very sensitive on the applied modeling parameters. Thus, we perform more elaborate large-eddy simulations (LES) for the analysis of this highly unsteady flow phenomenon. The simulations are validated against experimental data with the same parameter set and show excellent agreement. In the next step we will analyze the unsteady behavior to better understand the underlying flow physics and flow control mechanisms.

Impressum, Conny Wendler