Large Eddy Simulation of Self-Excited Oscillation Pulsed Jet (SEOPJ) Induced by a Helmholtz Oscillator in Underground Mining

Zhenlong Fang, Qiang Wu, Mengda Zhang, Haoyang Liu, Pan Jiang and Deng Li
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Zhenlong Fang: School of Energy and Power Engineering, Wuhan University of Technology, Wuhan 430063, China
Qiang Wu: School of Energy and Power Engineering, Wuhan University of Technology, Wuhan 430063, China
Mengda Zhang: School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
Haoyang Liu: School of Energy and Power Engineering, Wuhan University of Technology, Wuhan 430063, China
Pan Jiang: School of Energy and Power Engineering, Wuhan University of Technology, Wuhan 430063, China
Deng Li: School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China

Energies, 2019, vol. 12, issue 11, 1-20

Abstract: Pulsed waterjet can break rocks effectively by taking advantage of the water hammer effect, and is thus widely used in mining, petroleum, and natural gas fields. With the aim to further clarify the flow field characteristics of pulsed jets induced by a Helmholtz oscillator, large eddy simulation was conducted under different operating pressures. The velocity distribution, mean flow field, and the coherent structure were examined using the oscillators of different cavity lengths and diameters. The results clearly showed that the major frequency of jet pulsation gradually increased with the increase of operating pressure. A stable periodic velocity core was formed at the outlet of the Helmholtz oscillator, while the external flow field was subjected to periodic impact. As a result, the ambient fluid was strongly entrained into the jet beam. With the increase of the cavity length, the length of the core segment decreased while the energy loss caused by the cavity increased, which was also accompanied by a rapid attenuation of the axial velocity at the jet outlet. The coherent structure of the jet in the oscillator with small cavity diameter was more disordered near the nozzle outlet, and the vortex scale was larger. The effect of cavity diameter can be reflected in the feedback modulation of the jet in the cavity. Compared with the conical nozzle, the length of the core section of the jet was shorter, but the jet had better bunching, a smaller diffusion angle, and better mixing performance. These results provide a further understanding of the characteristics of pulsed water jet for better utilizations in the fields of energy exploitation.

Keywords: underground mining; pulsed waterjet; Helmholtz oscillator; large eddy simulation; coherent structure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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