Perforated Arc-Tabs for Jet Control

This paper presents the effectiveness of perforated arc tabs to enhance the mixing of axi-symmetric subsonic and sonic jets. Measurements of centerline velocity decay and velocity distribution in the directions along and normal to the tabs were carried out in the controlled jet, from a convergent nozzle with two arc-tabs placed at diametrically opposite locations at the nozzle exit, were carried out. Similar measurements were done for the uncontrolled jets, for comparison. Mach 0.6, 0.7, 0.9 and sonic jet at nozzle pressure ratios 2 and 3 were tested. It is found that the perforated arc-tabs greatly enhance the jet mixing of both subsonic and sonic jets. The core length comes down by 65%, 66%, 62% and 75%, for Mach 0.6, 0.7, 0.9 and correctly expanded Mach 1 jets, respectively.