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Browsing Research Outputs by Author "23rd Australasian Fluid Mechanics Conference (AFMC) (4 Dec 2022 - 8 Dec 2022 : Sydney)"

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    Experimental study of densely-seeded gravity-driven particle-laden flow
    (Australasian Fluid Mechanics Society, 2022) Bi, X.; Lau, T.; Sun, Z.; Nathan, G.; 23rd Australasian Fluid Mechanics Conference (AFMC) (4 Dec 2022 - 8 Dec 2022 : Sydney)
    Particles free-falling from a densely-seeded hopper with a rectangular outlet were experimentally studied utilising a combination of shadowgraphy and mass flow rate measurements. The study comprised a systematic assessment of the influence of the size of sintered bauxite particles (dp = 163, 192, 216, 257, 363, 399 and 500 μm) and hopper outlet thickness (D = 3, 4, 5 and 8 mm) on the particle distributions downstream from the hopper. A pulsed backlighting system comprising two CCD cameras synchronised with a LED panel was developed to image the particles within a falling distance of ≈ 1 m from the hopper exit. The mass flow rate of the particles was measured simultaneously with the imaging by recording the instantaneous weight of the hopper and its contents at a sampling rate of 1000 Hz. The results show that the particle distribution can be classified into three different regimes, namely a near-field expansion, a neck zone and an intermediate-field expansion. The expansion gradient of the near-field generally increases with the increase of dp and D, and was found to be strongly influenced by the exit particle Stokes number (SK₀). The intermediate-field expansion gradient decreases with the increase of dp, but was found to be insensitive to D, consistent with the current understanding of momentum-driven particle-laden jets. The classified flow regimes reveal the different dominant particle dynamics under different conditions, providing a guidance for the future in-depth studies of the various controlling mechanisms of free-falling particle flows.