Experimental study on the rock erosion performance of a pulsed abrasive supercritical CO2 jet

ABSTRACT An experimental study on the erosion behaviors of pulsed abrasive supercritical CO2 jets (PASJ) was performed using sandstone as the target specimen. The erosion depth, erosion area, and mass loss of the crater caused by PASJ were discussed in detail. The optimal configuration of the Helmholtz nozzle was first determined, and then influences of erosion-related working parameters including the jet pressure, abrasive particle size, ambient fluid and jet impingement angle on the rock erosion performance were analyzed with this nozzle. The results indicate that increasing jet pressure helps improve the erosion depth and area, which is mainly the result of increased jet kinetic energy. The erosion capability of PASJ is highly dependent on the size of abrasive particles. Coarser particles shows greater effectiveness in producing deeper erosion craters and the jets are more likely to retain rock-erosion ability as the standoff distance increases. At a given standoff distance, the crater eroded in air is deeper than those eroded in gaseous CO2 and in supercritical CO2, because the particles are slowed much more slowly in air under decreased drag. Moreover, the area of the crater eroded by PASJ in air is also largest due to the highest radial spreading rate. Finally, it was found that mass loss and erosion depth first increase and then decrease with the increase of jet impingement angle (θ) and the maximum values are reached at θ = 70o, whilst the erosion area increases monotonically with decreasing jet impingement angle.