LES OF CONVERGING-DIVERGING CHANNEL FLOW WITH SEPARATION

Abstract

The paper presents the results of LES simulation of two different turbulent channels with inlet conditions corresponding to the Reynolds number Re_τ = 395. In both cases a varying pressure gradient was obtained by an adequate curvature of one of the walls. The first case is treated as a benchmark and is used to validate the numerical procedure. This case is characterized by the same cross section area at the inlet and outlet and a bump of a smooth profile located on one of the walls designed to be identical to the one used in the experiment conducted at Laboratorie de Mecanique de Lille (LML) (Marquillie et al., 2008). The second case corresponds to the geometry which reproduces the real geometry of the turbomachinery test section of the Czestochowa University of Technology. The test section was created in such a way as to produce the pressure gradient which would correspond to the conditions present in the axial compressor blade channel. The shape of both channels produced initially favorable (FPG) and then adverse pressure gradients (APG), and in this way created conditions for boundary layer separation. Due to a reverse flow where the turbulence transport is dictated by the dynamics of the large-scale eddies such a case is well suited to demonstrate predictive features of the LES technique.