Study on influence of drill pipe rotation speed on coal particles-gas flow characteristics in negative pressure sampling process

doi:10.16265/j.cnki.issn1003-3033.2025.04.0998

Abstract

Abstract:

In order to investigate the impact of drill pipe rotation on coal particles transport efficiency during negative pressure sampling, CFD and DEM were used to explore the effects of drill pipe rotational speed and coal particles mass flow rate on gas-solid flow characteristics. The results show that: the maximum axial airflow velocity inside the drill pipe decreases and stabilizes as the transport distance increases, while the maximum tangential velocity rapidly decays and vanishes. As rotational speed increases, the axial airflow velocity remains largely unchanged, but the tangential velocity significantly increases. With higher rotational speed, the spiral flow of coal particles becomes more pronounced, the length of the vortex region increases, and the length of the suspension region decreases. The number of coal particles entering the drill pipe decreases, and the distribution of particles above 5 m/s increases and becomes more dispersed. During rotation, the actual solid-to-gas ratio inside the drill pipe is lower than the set value, and coal particles transport efficiency increases and then decreases with the rise in rotational speed.

Key words: negative pressure sampling, drill pipe rotating speed, coal particles, flow characteristic, computational fluid dynamics(CFD)-discrete element method (DEM) coupling

CLC Number:

X936

ZHANG Hongtu, ZHEN Zedong, LI Botao, ZHANG Ouya. Study on influence of drill pipe rotation speed on coal particles-gas flow characteristics in negative pressure sampling process[J]. China Safety Science Journal, 2025, 35(4): 94-100.

Figures/Tables 10

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网格数量	压降/Pa	最大误差/%
64 278	377	3.1
98 319	369
139 308	358
177 118	352

参数对象	数值
钢密度/(kg·m^-3)	7 400
钻杆转速/(r·min^-1)	0、50、100、150、200
取样风速/(m·s^-1)	20
煤屑直径/mm	2
煤屑密度/(kg·m^-3)	1 450
煤屑质量流量/(kg·s^-1)	0.01、0.02、0.03、0.04
煤屑—煤屑静摩擦因数	0.6
煤屑—煤屑动摩擦因数	0.05
煤屑—钢静摩擦因数	0.4
煤屑—钢动摩擦因数	0.05

工况	设定质量流量/ (kg·s^-1)	转速/ (r·min^-1)	设定固气比	实际固气比
1	0.01	0	0.48	0.32
2		50		0.375
3		100		0.36
4		150		0.33
5		200		0.34
6	0.02	0	0.95	0.64
7		50		0.76
8		100		0.71
9		150		0.63
10		200		0.61
11	0.03	0	1.43	0.81
12		50		0.85
13		100		0.77
14		150		0.61
15		200		0.54
16	0.04	0	1.90	0.82
17		50		0.85
18		100		0.77
19		150		0.61
20		200		0.54