Open Access

ARTICLE

Analysis of the Flow Field Characteristics Associated with the Dynamic Rock Breaking Process Induced by a Multi-Hole Combined External Rotary Bit

Quanbin Ba^1,2, Yanbao Liu^1,2,*, Zhigang Zhang^1,2, Wei Xiong^1,2, Kai Shen^1,2
1 State key Laboratory of Gas Disaster Monitoring and Emergency Technology, Chongqing, 400037, China
2 CCTEG Chongqing Research Institute, Chongqing, 400037, China
* Corresponding Author: Yanbao Liu. Email:
(This article belongs to this Special Issue: EFD and Heat Transfer III)

Fluid Dynamics & Materials Processing 2021, 17(4), 697-710. https://doi.org/10.32604/fdmp.2021.014762

Received 27 October 2020; Accepted 12 March 2021; Issue published 17 May 2021

Abstract

The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-ε turbulence model, and compared with the results of dedicated rock breaking drilling experiments. The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance, and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance. Moreover, the axial velocity related to the nozzle with inclination angle 20° and 30° can produce a higher hole depth, while the radial velocity of the nozzle with 60° inclination can enlarge the hole diameter. The outcomes of the CFD simulations are consistent with the actual dynamic rock breaking and pore forming process, which lends credence to the present results and indicates that they could be used as a reference for the future optimization of systems based on the multi-hole combined external rotary bit technology.

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Keywords

External rotation nozzle; RNG k-ε turbulence model; flow field characteristics; rock breaking and hole forming; process analysis

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