Effect of Initial Conditions on the Far Field of a Round Jet

The effect of initial conditions on the far field of a turbulent round jet (Rλ 450) has been examined using hot-wire mea-surements. Two types of initial conditions have been examined: the unperturbed jet, issuing from a nozzle in a laminar state, and the perturbed jet, where a woven grid is placed at the jet outlet in order to interfere with the initial development of the jet. Tur-bulent integral quantities and small scale characteristics show that the flow is partly reminiscent of the initial stages of the jet development, as modified by the grid. While the first- and second-order velocity statistics are affected only in terms of the virtual origin, length scales (such as the Kolmogorov and the Taylor scale) show also a different decay rate, under modified initial conditions. The similarity of the second-order structure functions is unaltered by the grid