Abstract
A coaxial jet has a higher potential to increase mixing between both its constituent fluids and the ambient fluid through increased spreading due to the presence of two shear layers. Factors like area ratio, inner jet velocity, velocity ratio, inner jet wall thickness, etc. influence the behavior of the coaxial jet to some degree. However, velocity ratio is the most critical parameter in dictating the flow regime of a coaxial jet. This study investigated the role of four different velocity ratios on the evolution of the vortices at both the shear layers. Their frequency is reported for all the cases, along with the size and shape of flow structures with the aid of flow visualisation. The interaction of the vortices originating from inner and outer shear layers is explored leading to the identification of a unique “mushroom” shaped structure in the inner shear layer for ru = 1.25. The effect of the vortices on the characteristics of coaxial jet like, potential core length and spreading angle are discussed. It was observed that the spreading angle consistently increased with increasing ru, 14° for ru = 0.75, 16° for ru = 1, and 18° for ru = 1.25, even surpassing that of a single jet (11.8°) of comparable size.
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Acknowledgements
The authors would like to acknowledge the support of Department of Science and Technology, India FIST Grant 2018.
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Samantaray, S.S., Arumuru, V. (2023). Effect of Velocity Ratio on Evolution of Vortices of a Coaxial jet. In: Bhattacharyya, S., Verma, S., Harikrishnan, A.R. (eds) Fluid Mechanics and Fluid Power (Vol. 3). FMFP 2021. Lecture Notes in Mechanical Engineering. Springer, Singapore. https://doi.org/10.1007/978-981-19-6270-7_73
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DOI: https://doi.org/10.1007/978-981-19-6270-7_73
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