point is located x=18 mm
Down stream the nozzle exit (x = 0 mm). The high shear between the rapid fuel jet and the circumfluent swirling air emanating from the annular slot gen- erates a second recirculation zone that reaches back into the nozzle. This can be seen from radial velocity profiles recorded at x = 1 mm (nozzle exit profiles) in Fig. 3 (top). Separation of the air flow from the conically shaped wall (cf. Fig. 1) will occur upstream of this recirculation bubble inside the nozzle. Radial velocity profiles downstream at x = 10 are presented in Fig. 3 (bottom). The spreading angle of the flow based on the maximum of the mean axial velocity component