(a)  kHz, side view

(b)  kHz, top view

Figure 5: Three-dimensional CLEAN-SC [13] sound maps obtained for the empty test section (position of the airfoil is indicated to enable comparison with Figure 4) (view from above, flow from left to right,  m/s, PPS 12/2 turbulence grid—position not indicated—mounted directly to the nozzle exit).