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According to the characteristics of high efficiency and high hole forming rate of the triangular-shaped drill pipe in the process of drilling in soft outburst coal seam, the slag discharge model of annular gap between the triangular-shaped drill pipe and hole wall is established by using the basic theory of computational fluid dynamics.Using the finite volume element method, the flow field characteristics of the annular flow area between drill pipe and hole wall are analyzed.Through the numerical simulation analysis, the velocity fluctuation effect of the annular flow field of the slag removal model is put forward, that is, the velocity fluctuation zone is formed between the sides of the arc edge of the triangular-shaped drill pipe, which causes the precipitated coal cinder to rise under the vortex action of the flow field, and is quickly discharged out of the hole under the coordination of the axial velocity, which effectively improves the slag removal efficiency and pore forming rate of the drill pipe.Finally, the comparative test of the triangular-shaped drill pipe and wide-blade spiral drill pipe was carried out in the soft outburst coal seam of 31021 lower auxiliary roadway in a mine. The drilling depth was increased by 19.4%, the hole forming rate was increased by 17.4%, and the drilling efficiency was increased by 26.4%. There was no drill drop and broken phenomenon.

Numerical Simulation Analysis Based on the Study of the Slag discharge Mechanism of the Triangular-shaped Drill Pipe