Examination of Reynolds number effect on the development of round jet flow

Keywords: Centerline velocity, Jet half-width, Potential core, Reynolds number, Round jet

Abstract

In this study, the Reynolds number effect on the development of round jet flow is presented. The jet is produced from a smoothly contracting round nozzle and the flow structure is controlled by varying the air blower speed in order to obtain various Reynolds numbers (Re). The flow Reynolds number considered varies between 1140 and 9117. Mean velocity measurements were taken using hot-wire probe at different axial and lateral distances (0≤x/d≤50, where x is the downstream distance and d is the nozzle diameter) for the jet flow and at for 0≤x/d≤30 in long pipe attached to the nozzle. Measurements reveal that Reynolds number dictate the potential core length such that the higher the Reynolds number, the lower the potential core which is a measure of mixing of jet and ambient fluid. It shows that further away from the jet exit section, potential core decreases as Reynolds number increases, the velocity profile has a top hat shape very close to the nozzle exit and the shape is independent of Reynolds number. It is found that potential core extends up to x/d=8 for Reynolds number of 1140 as against conventional near field 0≤x/d≤6. This may suggest effect of very low Reynolds number. However, further investigation is required to ascertain this at extremely low Reynolds numbers. It is also observed that further away from the jet exit section, the higher the downstream distance, the higher the jet half-width (R1/2). Furthermore, the flow in the pipe shows almost constant value of normalised axial centerline velocity for a longer distance and this clearly indicates that there is mass redistribution rather than entrainment of ambient fluid. Overall, the Reynolds number controls the magnitude rather than the wavelength of the oscillation

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Author Biographies

Olanrewaju Miracle Oyewola, Fiji National University; University of Ibadan

School of Mechanical Engineering

Department of Mechanical Engineering

Adebunmi Okediji, University of Ibadan; Elizade University

Department of Mechanical Engineering

Department of Mechanical Engineering

Olusegun Olufemi Ajide, University of Ibadan

Department of Mechanical Engineering

Muyiwa Samuel Adaramola, Norwegian University of Life Sciences

Faculty of Environmental Sciences and Natural Resource Management

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Published
2021-11-18
How to Cite
Oyewola, O. M., Okediji, A., Ajide, O. O., & Adaramola, M. S. (2021). Examination of Reynolds number effect on the development of round jet flow. EUREKA: Physics and Engineering, (6), 39-47. https://doi.org/10.21303/2461-4262.2021.001872
Section
Chemical Engineering

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