The near field of a fully turbulent circular jet

Abstract

The near-field measurement of fully turbulent jets discharged from a straight circular pipe indicates the presence of quasiperiodic velocity perturbations. The Strouhal number based on the predominant frequency falls in the range of the preferred mode for the jet with a potential core and has an asymptotic value of 0.38 in the high Reynolds number regime. Regular perturbations are not observed in the mixing region immediately downstream from the pipe exit.

Manipulation of vortex rings for flow control

“…The generation of the coherent structures is predicted by the linear stability analysis of mean velocity profile (Wygnanski and Petersen 1987). The Strouhal number measured for the jet developing from fully developed pipe flow is 0.38 (Hayakawa et al 1985), which agrees with the value predicted by the instability theory (Crighton and Gaster 1976).…”

Turbulent Two-Dimensional Shear Flows

“…If the exit profile is laminar, but undeveloped, the best way to deal with this case is to consider that the core part of the profile is described by a constant velocity and that a (half) gaussian can be fitted to the sides of the profile (Mattingly & Chang, 1974). This is the case of a fully turbulent jet discharging from a straight pipe (Hayakawa et Al., 1985). A round jet is not necessatily of the uniform type: the flow may be fully turbulent across the exit plane, so that no potential core is present (Boguslawski & Popiel, 1979).…”