Flapping Motion of a Turbulent Jet Under the Asymmetric Excitation of Two Unsteady Minijets

摘要

The control of a turbulent round jet is experimentally investigated based on the injection of two radial minijets, separated azimuthally by an angle θ = 60°, prior to the issue of the main jet. It has been found that the asymmetric excitation increases the decay rate of the jet centerline mean velocity by 30% or more than the symmetric (θ = 180°). A flapping motion of the jet column is found to be responsible for the substantially increased jet mixing.