Near-field behavior of variable property jet with swirling flow generated by a change in gravitational orientation

Adzlan, A. and Tsutsumi, S. and Gotoda, H. (2015) Near-field behavior of variable property jet with swirling flow generated by a change in gravitational orientation. Physics of Fluids, 27 (2). ISSN 1070-6631

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Abstract

This paper presents the near-field behavior of a variable property jet with swirling flow generated by a change in gravitational orientation, focusing on the onset of vortex formation at the jet interface and the subsequent vortex breakdown (VB). Two types of gases are used to create a significant difference in the physical properties between the inner and outer fluids: CO2 with high-density and low-viscosity, and helium with low-density and high-viscosity. We propose a nondimensional instability parameter M* as a useful index for predicting the onset of vortex formation at a swirling jet interface. Inverted gravity (+1g) enlarges the region of unstable VB of the CO2 jet compared with that in normal gravity (-1g), which clearly shows that the buoyancy force has a significant impact on unstable VB. The trends of the changes in the jet half-angle and stagnation point height are investigated in detail for the preceding stable VB. Our physical model derived by considering the momentum balance in a swirling flow is adopted to understand the mechanism of the notable change in the stagnation point height in +1g with increasing swirl number of the inner jet and Reynolds number of the outer jet.

Item Type: Article
Uncontrolled Keywords: ravitational orientation; High viscosities; Momentum balances; Normal gravities; Stagnation points; Variable property; Vortex breakdown; Vortex formation, unimas, university, universiti, Borneo, Malaysia, Sarawak, Kuching, Samarahan, ipta, education, research, Universiti Malaysia Sarawak
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Academic Faculties, Institutes and Centres > Faculty of Engineering
Depositing User: Karen Kornalius
Date Deposited: 01 Aug 2016 02:59
Last Modified: 24 Feb 2017 01:49
URI: http://ir.unimas.my/id/eprint/12729

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