Investigation of the dynamic ascent characteristics of ice core during polar core drilling

In polar ice core drilling, continuous coring with air reverse circulation (CCARC) technique can increase the drilling rate, reduces pollution, and prevents air circulation loss. Dynamic collisions occur between ice chips and ice core in the drilling process, resulting in changes in the ice core ascent characteristics. Based on this, the Computational Fluid Dynamics-Discrete Element Model (CFD-DEM) coupling analysis method is used to simulate mixed flow ascent during continuous coring with air reverse circulation. This paper investigates the ice core ascent characteristics with consideration of the influence of the dynamic interaction mechanism between ice core and ice chips. The results show that the contact force of the ice core due to ice chip collision plays an essential role in the ascent. The contact force considering the ice chips influences, the drag force increases 23–85% compared with without. With the reduction of air mass flow rate, the impact of contact force is more significant. The dynamic collision between ice chips and the ice core reduces the pressure drop. The contact force and pressure drop are used as the performance indexes of the influence of ice chips on the ice core. Air mass flow rate has the most significant impact on the contact force and pressure drop. Other factors greatly influence the contact force but have little influence on the pressure drop. This paper considers the influence of ice chips on the ice core ascent during the air reverse circulation drilling (ACD) process. Traditional ice core ascent models do not consider dynamic interaction mechanisms, leading to inaccurate results. The research results provide an essential reference value for polar core drilling.