Visualized Turbulent Jet under the Manipulation of Unsteady Minijets

Yu Zhou

Institute for Turbulence-Noise-Vibration Interactions and Control

Shenzhen Campus, Harbin Institute of Technology, China

Abstract

A turbulent round jet is experimentally manipulated using 1-6 unsteady radial minijets injected prior to the issue of main jet. The decay rate of the jet centerline mean velocity under manipulation may reach more than 11 times that in the natural jet and is found to depend strongly on the minijet configuration, the ratio of the minijet excitation frequency to the main jet preferred-mode frequency, the mass flow rate ratio of each minijet to the main jet, and the nozzle diameter ratio of the minijet to the main jet. Two mechanisms behind the highly effective manipulation are identified from extensive flow visualization data captured in three orthogonal planes, along with the PIV data. One is the jet column flapping associated with asymmetric minijet injection, which increases dramatically the spread along the flapping direction. The other is identified for symmetric minijet injection, characterized by rapidly and sequentially ‘tossed-out’ mushroom-like structures along the mid plane between minijets. Conceptual models of the corresponding flow structures are proposed. An empirical scaling analysis is also conducted, along with a discussion on the Reynolds number effect on the jet control.

 

Curriculum Vitae

Professor Yu Zhou completed his PhD degree at The University of Newcastle in 1993. He was a Full Professor at The Hong Kong Polytechnic University and has since 2013 been the Full Professor and Director of the Institute of Turbulence-Noise-Vibration Interaction and Control at the Harbin Institute of Technology (Shenzhen). His main research interests are experimental studies of turbulent flows (wakes, jets, boundary layers, complex flows), flow-induced vibrations and active flow control. He has published over 160 archival journal papers, including 26 in the Journal of Fluid Mechanics. His work has received about 2400 ISI citations. He was the recipient of the prestigious Chinese national “1000 Talent Scheme” award in 2010 and was elected to be the Fellow of Australasian Fluid Mechanics Society in 2014. He serves as Associate Editor of AIAA Journal.