ORCID

Abstract

A wall-bounded dual jet, consisting of a wall jet and a co-flowing offset jet, possesses a complex flow structure that has proved advantageous across many industrial applications. Despite this, dual jets remain relatively unexplored through experimentation and their flow phenomena are largely misunderstood. This investigation is the first to examine the effect of varying the velocity ratio (Vr) on the flow and heat transfer behaviour of a dual jet through experimental means. A velocity ratio range of 0.5≤Vr≤2 is achieved by varying each jet Reynolds number (Rew/o) in the range 5500≤Rew/o≤12,000. Infrared thermography is used to acquire the local Nusselt number (Nux) profile along the bounding wall when subject to a uniform wall heat flux of 1670 W/m2 for the offset ratio range 1≤OR≤7. In tandem, a particle image velocimetry study collects the corresponding flow data for 1≤OR≤3. For Vr<1, the wall jet is pulled farther from the boundary, increasing the extent of the separation region and moving the locations of the local minimum and maximum values in the Nux profile either downstream (OR=1) or upstream (OR≥3), which in turn affects their respective magnitudes. For Vr>1, the separation of the wall jet becomes increasingly suppressed and the Nux profile approaches that of a single wall jet, where the ‘peaking’ effect previously observed for OR=1 is no longer apparent. The time-resolved data shows an increasing Strouhal number (St) associated with the vortex shedding frequency for OR=2 and OR=3 within a limiting Vr range, however a general decline is observed for OR=1.

Keywords

Dual jets, Offset jet, Particle image velocimetry, Turbulent jets, Wall jet

Publication Date

2025-01-01

Publication Title

Thermal Science and Engineering Progress

Volume

66

Deposit Date

2026-03-04

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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