Hot-point drills have been widely used for drilling boreholes in glaciers, ice caps and ice sheets. A hot-point drill melts ice through the thermal head at its bottom end. Penetration occurs through a close-contact melting (CCM) process, in which the ice is melted, and the meltwater is squeezed out by the exerted force applied on the thermal head. During the drilling, a thin water film is formed to separate the thermal head from the surrounding ice. For the hot-point drill, the rate of penetration (ROP) is influenced by several variables, such as thermal head shape, buoyancy corrected force (BCF), thermal head power (or temperature) and ice temperature. In this study, we developed a model to describe the CCM process, where a constant power or temperature on the working surface of a thermal head is assumed. The model was developed using COMSOL Multiphysics 5.3a software to evaluate the effects of different variables on the CCM process. It was discovered that the effect of thermal head shape and the cone angle of conical thermal head on ROP is less significant, whereas the increase in the BCF and the power (or temperature) of the thermal head can continuously enhance the ROP.

中文翻译：

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冰中热点钻探建模

热点钻机已广泛用于在冰川、冰盖和冰盖中钻孔。热点钻通过其底端的热头融化冰。渗透通过紧密接触融化 (CCM) 过程发生，在该过程中，冰被融化，融水被施加在热敏头上的力挤出。在钻井过程中，会形成一层薄薄的水膜，将热压头与周围的冰层隔开。对于热点钻，钻速 (ROP) 受几个变量的影响，例如热头形状、浮力校正力 (BCF)、热头功率（或温度）和冰温。在这项研究中，我们开发了一个模型来描述 CCM 过程，其中假设热敏头工作表面上的功率或温度恒定。该模型是使用 COMSOL Multiphysics 5.3a 软件开发的，用于评估不同变量对 CCM 过程的影响。研究发现，热头形状和锥形热头的锥角对ROP的影响较小，而BCF和热头功率（或温度）的增加可以不断提高ROP。