Turbulent jet from a slender annular slot ventilated by a self-induced flow through the open core

Shahid A. Padhani, Gary R. Hunt, and Timothy N. Jukes
Phys. Rev. Fluids 3, 014602 – Published 10 January 2018

Abstract

The dynamics of an incompressible turbulent air jet from an annular source into otherwise quiescent surroundings are investigated. Focusing on a slender annulus with an open core, the development of the jet is examined using planar and stereoscopic particle image velocimetry (PIV) from the source to 16 (outer) source diameters downstream. Unique to these annular sources, the jet induces a flow through the open core—in other words, the core is “ventilated.” Our measurements indicate that the volume flux drawn through the core exceeds that from the source by approximately 20%. Based on the streamwise development of the jet, we identify four distinct regions: (i) an internal region of induced flow that is bounded by the jet; (ii) a near-field planar-jet-like region; (iii) a transition region; and, ultimately, (iv) a far-field round-jet-like region. We explore the evolution of the jet toward self-similar behavior based on cross-stream profiles of time-averaged velocity and turbulence statistics within these different regions. Four distinct length scales are shown to characterize the streamwise extents and behaviors within the regions identified. Finally, to highlight the role of the open-core (ventilated) annular geometry on jet development, comparisons are made with PIV measurements of turbulent jets issuing from circular sources. These comparisons reveal that the ventilated geometry significantly enhances dilution in the near field.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
14 More
  • Received 27 July 2017

DOI:https://doi.org/10.1103/PhysRevFluids.3.014602

©2018 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

Shahid A. Padhani1, Gary R. Hunt1,*, and Timothy N. Jukes2

  • 1Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, United Kingdom
  • 2Aero-acoustic Research, Dyson Technology Ltd., Malmesbury, Wiltshire, SN16 0RP, United Kingdom

  • *gary.hunt@eng.cam.ac.uk

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 3, Iss. 1 — January 2018

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Fluids

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×