Thesis defence V. Gentile: turbulence

24 April 2017 12:30 - Location: Aula, TU Delft - By: Webredactie

Turbulent Axisymmetric Base Flows- Symmetry and Long Term Behavior. Promotor: Prof.dr. F. Scarano (LR).

Abstract: The behavior of the turbulent flow past a blunt-based body of revolution is relevant to many aerospace transportation systems, notably to space launcher vehicles. The base geometry in these configurations induces a separated wake flow behind the body, which comprises a free shear layer and an inner region of lower-speed recirculating flow. The present work surveys the behavior of the turbulent flow downstream of a truncated rocket model by means of time-resolved particle image velocimetry (PIV) measurements. The long-term meandering of the recirculation region about the symmetry axis of the body tends to dominate the wake dynamics close to the base. The fluctuations associated with the shear layer development instead, tend to prevail more downstream. The erratic behavior of the recirculation region is attributed to the symmetry of the inflow conditions and is inhibited by the presence of small angular misalignments between the body and the incoming flow. The presence of a rear central protrusion, such as a propulsive nozzle, is shown to have a major influence on the wake dynamics and can disrupt the coherence of the wake fluctuations even for relatively small diameters. The symmetry of the base plays a further important role in the flow reattachment process particularly with respect to its scaling.

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