Title: Computation of a drastic flow pattern change in an annular swirling jet caused by a small change in inlet swirl
Authors: Vanierschot, Maarten ×
Van den Bulck, Eric #
Issue Date: Feb-2009
Publisher: John Wiley & Sons LTD
Series Title: International Journal for Numerical Methods in Fluids vol:59 issue:5 pages:577-592
Abstract: This paper investigates the flow pattern change in an annular jet caused by a sudden change in the level of inlet swirl. The jet geometry consists of an annular channel followed by a specially designed stepped-conical nozzle, which allows the existence of four different flow patterns as a function of the inlet swirl number. This paper reports on the transition between two of them, called the ‘open jet flow high swirl’ and the ‘Coanda jet flow.’ It is shown that a small sudden decrease of 4% in inlet swirl results in a drastic and irreversible change in flow pattern. The objective of this paper is to reveal the underlying physical mechanisms in this transition by means of numerical simulations. The flow is simulated using the unsteady Reynolds-averaged Navier–Stokes (URANS) approach for incompressible flow with a Reynolds stress turbulence model. The analysis of the numerical results is based on a study of different forces on a control volume, which consists of the jet boundaries. The analysis of these forces shows that the flow pattern change consists of three different regimes: an immediate response regime, a quasi-static regime and a Coanda regime. The simulation reveals that the pressure–tangential velocity coupling during the quasi-static regime and the Coanda effect at the nozzle outlet during the Coanda regime are the driving forces behind the flow pattern change. These physical mechanisms are validated with time-resolved stereo-PIV measurements, which confirm the numerical simulations.
ISSN: 0271-2091
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Applied Mechanics and Energy Conversion Section
Mechanical Engineering Technology TC, Campus Group T Leuven
Technologiecluster Werktuigkundige Industriƫle Ingenieurstechnieken
× corresponding author
# (joint) last author

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