Experimental Investigation of the Unsteady Flow Behavior on a Film Cooling Flat Plate

Combined Experimental and CFD Investigation of Flat Plate Film Cooling through Fan Shaped Holes

“…Tests have been carried out at low speed, about 15 m/s, and low inlet turbulence intensity level below 1.0%, for blowing ratio (BR) values of 1 and 2. A detailed description of both wind tunnel and test conditions is provided in [12]. The film cooling scheme consisted of a row of three fan-shaped holes with 5 mm diameter ( Figure 1).…”

“…Normalized mean velocity flow fields in the near-hole region are shown in Figure 8, for BR of 1 The next step consisted in measuring the boundary layer downstream of the mid-hole at hole centerline by means of the LDV technique. Details on LDV measurements are given in [12]. Results from LDV measurements at hole centerline are reported in Figures 6 and 7 in terms of profiles of time-averaged streamwise velocity component as well as streamwise and wall normal rms velocities at X/D = 1 and = 5, respectively ( Figure 1).…”

“…Also, the velocity profile was relatively flat downstream of the hole. PIV technique (for more details refer again to Rouina et al [12]) was used to characterize the mean and turbulent flow distribution over a stream-wise plane located at mid hole centerline (Z/D = 0). Normalized mean velocity flow fields in the near-hole region are shown in Figure 8, for BR of 1 PIV technique (for more details refer again to Rouina et al [12]) was used to characterize the mean and turbulent flow distribution over a stream-wise plane located at mid hole centerline (Z/D = 0).…”

“…Doubling the BR caused a slight reduction in ηave within X/D < 7, despite some minor improvements in ηave far from the hole exit. Flow visualizations (see again [12]) were also performed on the same plane to investigate the mixing process between the coolant and the mainstream (Figure 9). The unsteady nature of the jet interaction with the mainstream is documented by the presence of large coherent structures at the jet boundaries.…”

“…Contours of η obtained by injecting nitrogen as the coolant stream, are depicted in Figure 10. For both BR, the jet is attached to the flat plate surface and spreads out laterally to ensure a more effective thermal protection compared to the cylindrical hole [12]. The centerline effectiveness, as a function of the distance from the hole, indicates that the fan-shaped hole provides values of η cl > 0.7 within X/D < 5, for both BR (Figure 11).…”