Investigating One-Dimensional Turbulence Intensity of Circular and Non-Circular Jets

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International Journal of Research and Scientific Innovation (IJRSI) | Volume VI, Issue XII, December 2019 | ISSN 2321–2705

Investigating One-Dimensional Turbulence Intensity of Circular and Non-Circular Jets

Kyaw Hla Saing Chak1*, Kazi Rifat Bin Rafiq1, Md. Samrat Hossain1, Shafi-Al-SalmanRomeo1, Md. Thariqul Islam1

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1Department of Aeronautical Engineering, Military Institute of Science and Technology, Mirpur Cantonment, Dhaka-1216, Bangladesh
*Corresponding Author

Abstract ─ Fluid dynamics and heat transfer sectors have undergonerevolutionary improvements with the study of turbulent flow in recent decades and still different ongoing researches are making breakthroughs in those sectors. In this research, the fluctuation of pressure in the flow field was measured using differential pressure transducer to investigate the turbulence region of conventional circular jet as well as non-circular (rectangular, square and triangular) jets in the flow axis only. The method was approached to introduce a cost-efficient technique as the alternative of high- cost particle image velocimetry, acoustic Dopplervelocimetry. The objective was to investigate the change in turbulence characteristics of different jets and compare performance which can be applied to aerodynamics, propulsion, heat transfer or environmental studies. Simultaneous measurements of pressure in the flow field were taken using pitot-tube which was converted into velocity applying dynamic pressure theory. The jet flow was created using a blower in an airflow facility and the area of inlet and outlet of all the nozzle was equal to maintain the initial jet flow characteristics. The turbulent intensity, mean shear layer and potential core length of the jets have been derived from the measured data. The study revealed that square nozzle didn’t have a significant impact in the flow field whereas the rectangular jet had an increased average shear layer and the triangular jet had a decreased potential core length compared to the conventional jet.

Keywords ─Jet, Turbulence, Differential pressure, Circular Jet, Shear region, Aerodynamics.

I. INTRODUCTION

A shear region is produced between the moving and ambient fluids when the fluid at motion enters a quiescent body of the same fluid, causing turbulence. Turbulence dominates all other flow parameters and enhances flow mixing, energy dissipation, drag and heat transfer. Most of the flows encountered in nature, e.g.: flow over an aircraft wing, atmospheric boundary layer over the earth’s surface and oceanic currents are all turbulent in nature [1,2]. During the 1960s, research on turbulence has been conducted to discover some deterministic features that revealed the bursting process in the near-wall region produced most of the turbulent energy [3].