Preconditioning of rock for drilling operations is a potential method to facilitate the mechanical breakage and mitigate the tool wear. This paper numerically investigates one such preconditioning technique, namely, the thermal jet assisted rock cutting. For this end, a numerical method for solving the governing thermo‐mechanical problem is developed and validated. The continuum approach is chosen to describe the rock failure, being based on a damage‐viscoplasticity model with the Drucker–Prager yield surface and the modified Rankine surface as the tensile cut‐off. In the damage part, separate scalar damage variables are employed for tension and compression. The cutters are modelled as rigid bodies and their interaction with the rock is modelled by imposing contact constraints by the forward increment Lagrange multiplier method, which is compatible with the chosen explicit time integration scheme. A damage‐based erosion criterion is applied to remove the contact nodes surrounded by heavily damaged elements. The thermal jets are modelled with a moving external heat flux boundary condition. The global thermo‐mechanical problem is solved with a staggered approach explicitly in time while applying mass scaling to increase the critical time step. The novel 3D numerical simulations involving two cutters demonstrate the capabilities of the method with a special emphasis on cutter‐thermal jet configurations. Therefore, the present method provides a potential tool for the bit design in thermal jet assisted drilling.

中文翻译：

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双 PDC 刀具热射流辅助岩石切削的数值模拟

用于钻井作业的岩石预处理是促进机械破碎和减轻工具磨损的潜在方法。本文对一种这样的预处理技术进行了数值研究，即热射流辅助岩石切割。为此，开发并验证了一种解决控制热机械问题的数值方法。选择连续介质方法来描述岩石破坏，该方法基于损伤粘塑性模型，以 Drucker-Prager 屈服面和修正的朗肯曲面作为拉伸截止。在损伤部分，拉伸和压缩采用单独的标量损伤变量。刀具被建模为刚体，它们与岩石的相互作用通过前向增量拉格朗日乘子法施加接触约束来建模，该方法与所选择的显式时间积分方案兼容。应用基于损坏的侵蚀准则来去除被严重损坏单元包围的接触节点。热射流采用移动的外部热通量边界条件进行建模。全局热机械问题通过时间上明确的交错方法解决，同时应用质量缩放来增加关键时间步长。涉及两个刀具的新颖 3D 数值模拟展示了该方法的功能，特别强调刀具热射流配置。因此，本方法为热射流辅助钻井中的钻头设计提供了潜在的工具。