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Large Eddy Simulation of Self-Excited Oscillation Pulsed Jet (SEOPJ) Induced by a Helmholtz Oscillator in Underground Mining
被引:22
作者:
Fang, Zhenlong
[1
]
Wu, Qiang
[1
]
Zhang, Mengda
[2
]
Liu, Haoyang
[1
]
Jiang, Pan
[1
]
Li, Deng
[2
]
机构:
[1] Wuhan Univ Technol, Sch Energy & Power Engn, Wuhan 430063, Hubei, Peoples R China
[2] Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Hubei, Peoples R China
来源:
基金:
中国国家自然科学基金;
关键词:
underground mining;
pulsed waterjet;
Helmholtz oscillator;
large eddy simulation;
coherent structure;
SUSTAINED OSCILLATIONS;
FLOW;
D O I:
10.3390/en12112161
中图分类号:
TE [石油、天然气工业];
TK [能源与动力工程];
学科分类号:
0807 ;
0820 ;
摘要:
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.
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页数:20
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