title: Turbulent jet manipulation using two unsteady azimuthally separated radial minijets.
abstract: The active manipulation of a turbulent round jet is experimentally investigated based on the injection of two radial unsteady minijets, prior to the issue of the main jet. The parametric study is conducted for the mass flow ratioCmof the minijets to the main jet, and the ratiofe/f0of the minijet frequency to the preferred-mode frequency of the main jet. It is found that the decay rate of the jet centreline mean velocity could be greatly increased if the two minijets are separated azimuthally by an angleθ=60°, instead of byθ=180°. This increase is a consequence of the flapping motion of the jet column, and the formation process and generation mechanism of this flapping motion are unveiled by careful analysis of the experimental data.
authors: Institute for Turbulence-Noise-Vibration Interactions and Control, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, People's Republic of China; Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
authors: H
authors: 0000-0002-1540-1793
authors: H
authors: Yang
authors: Institute for Turbulence-Noise-Vibration Interactions and Control, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, People's Republic of China; Digital Engineering Laboratory of Offshore Equipment, Shenzhen, People's Republic of China.
authors: Y
authors: Y
authors: Zhou
authors: Department of Mechanical Engineering , The Hong Kong Polytechnic University , Kowloon, Hong Kong.
authors: R M C
authors: RM
authors: So
authors: Department of Mechanical Engineering , The Hong Kong Polytechnic University , Kowloon, Hong Kong.
authors: Y
authors: Y
authors: Liu
keywords: active jet control; asymmetric excitation; flapping jet; unsteady minijet