Jet flow control using semi circular corrugated tabs

Abstract

Research on high speed jet control is of primary significance to aerospace as well as in the analogous fields Jet control is necessary for the following reasons a to suppress the noise during take off and landing b to augment the air fuel mixing in the combustor c to control the rocket direction by Thrust Vector Control TVC d to reverse the direction of thrust in aircrafts during landing High speed jets can be controlled by two methods namely active control and passive control The usage of auxiliary power is used in active control whereas the energy is harnessed from the flow itself in the passive control method In the present study passive control technique is adopted to control the jet The following are some of the methods used in the controlling of high speed jets by passive technique splitter plates usage of trip wires tabs at nozzle exit non circular jets etc In this research work the jet is controlled by introducing the tabs at the exit of the nozzle A tab is a small strip flap of solid material inserted into the passage of the flow It incites paired vortices which are counter rotating effecting the jet flow development mass entrainment and jet spread This thesis presents the experimental study to investigate the jet mixing characteristics of semi circular corrugated tabs In this regard three semi circular corrugated triangular tabs Tab A Tab B and Tab C of equal blockage 5 12 with respect to the exit diameter of the nozzle in which the corrugation locations are varied along the leaned edges of the triangular tab is used The triangular tab is effective to shed vortices of sizes that vary continuously from largest to smallest There is a creation of interaction of vortices which eventually results in reduced near field mixing which is proved to be an advantage When semi circular corrugations are made along the sides of the isosceles triangular tab they develop two sharp edges at their locations