Theoretical and numerical simulation research about annular nozzle parameters influence on heat transfer in hot-water ice-coring drilling

Abstract

Ice cores from polar zones could determine ice dating and biodiversity. Ice cores retrieved in hot-water ice-coring drilling partly melted owing to moderate drilling speed of annular drill head with many nozzles, which was largely depended on the heat transfer efficiency of jet to ice at borehole bottom. To obtain the higher drilling speed and ice cores of good quality, this paper explored the influence of nozzle parameters on the heat transfer efficiency of annular jet to bottom ice. Main nozzle parameters affecting the heat transfer efficiency were theoretically determined firstly. Then influence law of nozzle parameters on the heat transfer were estimated by theoretical calculation and numerical simulation. The result showed the heat transfer of annular jet to bottom ice was positively correlated with the nozzle flow and negatively relevant with the nozzle diameter, nozzle angle and nozzle quantity, which was further compared with the drilling speed value in experiment to confirm its correctness. The angle was proved to be the most influential parameter, when it increased from 0° to 30°, the drilling speed decreased 75%. The result can provided reference for designers on how to promote the drilling speed in hot-water ice-coring drilling and improve ice core quality.

Keywords

• Polar research
• Hot-water ice-coring drilling
• Nozzle parameters
• Heat transfer
• Drilling speed