Large-Eddy Simulations of trailing-edge cutback film cooling at low blowing ratio

Experimental investigation of the effects of blowing conditions and Mach number on the unsteady behavior of coolant ejection through a trailing edge cutback

“…On the other hand, a visual inspection of several pictures showed that the above commented ''mushroom like'' vortical structure is the dominant feature of the coolant mixing process at this MFR slot . Actually this is a confirmation of the numerical results obtained by Schneider et al (2010) that for a VR = 0.83 (in the present case for MFR slot = 1.07% the corresponding VR is about 0.79, see Fig. 7 or Table 2) found exactly the same flow feature.…”

“…At author's knowledge, this is the first experimental evidence of the existence of large, coherent vortical structures that are shed by the cutback lip for a real geometry subjected to a strong accelerating flow. Similar vortical structures were only previously documented by numerical investigations (Holloway et al, 2002b;Martini et al, 2005b;Schneider et al, 2010). These large coherent structures, together with the complex slot internal geometry, are responsible for the low film cooling effectiveness values observed even close to the slot exit, since they drive the main flow close to the wall (Fig.…”

“…The documented instantaneous temperature distributions downstream of the lip indicated a strong impact of the internal slot geometry on the unsteady mixing process. To deeply study this aspect, Schneider et al (2010) applied LES to a similar slot model tested at low blowing ratios. They showed the presence of both small and large scale structures, the latter dominating the coolant to mainstream mixing process.…”

Coherent structures in trailing-edge cooling and the challenge for turbulent heat transfer modelling

“…In contrast, the use of a hybrid LES/RANS method including the Scale-Adaptive Simulation (SAS) method of Menter and Egorov (2010) allowed to capture the large-scale unsteadiness and its effect on heat transfer more realistically, so that the calculations yielded a significantly better agreement with the corresponding experiments (Martini et al, 2006b;Joo and Durbin, 2009;Egorov et al, 2010). Schneider et al (2010) investigated by means of highly-resolved LES the role of large-scale unsteadiness for a trailing-edge design without internal turbulators corresponding to an experiment of Martini (2008). For the two blowing ratios M ¼ 0:5 and 1.1 considered, an experimentally observed counter-intuitive behaviour could be reproduced, i.e.…”

Comparative study of large eddy simulation of film cooling using a dynamic global-coefficient subgrid scale eddy-viscosity model with RANS and Smagorinsky Modeling

“…Film cooling effectiveness depends on many parameters like cooling hole shape, cooling hole inclination, arrangement of row of holes, properties of mainstream fluid, coolant to mainstream blowing ratio, density ratio and momentum flux ratio. Accordingly most of the numerical studies [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] in literatures have been performed to investigate the effects of aforementioned parameters on film cooling flows and less concentration on more accurate numerical simulation of film cooling problems is made especially in Large eddy Simulation [18][19][20][21][22][23][24][25][26]. In this paper, a new eddy-viscosity subgrid-scale model proposed by You and Moin [1] was used for large-eddy simulation of a film cooling flow.…”