Library Subscription: Guest
Begell Digital Portal Begell Digital Library eBooks Journals References & Proceedings Research Collections
TsAGI Science Journal

ISSN Print: 1948-2590
ISSN Online: 1948-2604

TsAGI Science Journal

DOI: 10.1615/TsAGISciJ.2016017878
pages 111-137

INVESTIGATION OF THE FLOW STRUCTURE AND ACOUSTIC FIELD OF A TURBULENT JET WITH HIGH SWIRLING INTENSITY

Sergei Yu. Krasheninnikov
Central Institute of Aviation Motors (CIAM), 2 Aviamotornaya St., Moscow, 111116, Russia
Vladimir Pavlovich Maslov
Central Institute of Aviation Motors (CIAM), 2 Aviamotornaya Str., Moscow, 111116, Russian Federation
Aleksey Konstantinovich Mironov
Central Institute of Aviation Motors (CIAM), 2 Aviamotornaya St., Moscow, 111116, Russia
Pavel Damirovich Toktaliev
Central Institute of Aviation Motors (CIAM), 2 Aviamotornaya St., Moscow, 111116, Russia

ABSTRACT

The flow structure and acoustic field of free turbulent jets with high swirling intensity (W0) are experimentally studied. Under these conditions, a recirculation flow exists in the paraxial region of the jet and a tonal sound is emitted. The averaged and nonstationary characteristics of the jet flow, precession motion, and velocity and pressure fluctuations are investigated. The study is based on using constant-temperature anemometry and particle image velocimetry with conditional phase averaging. Flows behind various swirling devices are analyzed. It is shown that the main properties of the averaged flow are determined by the intensity of flow swirling in the source (W0). This fact allows the investigations to be limited by one source of the swirling jet. Unsteady flow in the jet and near the jet boundary is also simulated numerically. The results of the present investigations show that the jet flow structure is determined by the swirling intensity, which governs the configuration of the recirculation zone and precession of dynamic non-uniformities with respect to the jet axis. The precession frequency coincides with the first frequency of the discrete tone (f0), which is adequately described by the general formula Sh = f0d = u0 = 0.7W0 , where d is the exit diameter and u0 is the averaged exhaustion velocity. The precession motion in the jet generates oscillations of air inflowing to the jet with the same frequency f0. The acoustic field is formed approximately at a distance of 5-10d from the jet boundary. The results of the present investigations suggest a relationship between jet noise generation and flow rate oscillations in the flow ejected by the jet.