Abstract
Effects of a jet perturbation on mixing performance of an air-jet array were investigated experimentally. The jet array consists of three same-sized parallel jets, and the mass flow rate of the central jet is perturbed in a pulsatile or a sinusoidal cycle with the frequency, fr = 0, 1 or 2Hz. The aligned jets issued simultaneously without the jet perturbation (fr = 0Hz) shows good mixing performance in comparison with the jet array of three arithmetically-superimposed single jets. The flow condition with the jet perturbation (fr = 1 or 2Hz), on the other hand, is alternately changed, laminar or turbulent, in one cycle of the central jet perturbation. The time-averaged velocity profiles of the jet array obtained under certain perturbed conditions demonstrate an adverse change of the mixing performance at the locations near the nozzle and far downstream. Phase-averaged velocity profiles were thoroughly examined in order to understand such a mixing mechanism of the multiple jet flow.
