Effect of Air Gap in Borehole on Directional Penetration of Shaped Charge with/without Metal Liner

In order to explore the influence of the radial air gap in the hole on the directional penetration effect of shaped charge with/without metal liner and the detonation energy transfer process of explosive，ANSYS/LS-DYNA software was used to carry out the numerical simulation study when the air gap of the charge in the hole was 6，8，10，12，14 cm. The process of central- ized release of energy from the shaped charge with metal liner forming an EFP and without metal liner forming concentrated deto- nation product flow as well as the depth of directional penetration into the borehole wall，was analyzed. The results show that when the air gap is less than 10 cm，the penetration depth of concentrated detonation product flow into the hole wall is in- creased by 53%（6 cm）and 29%（8 cm），respectively，compared with the average penetration depth of EFP. When the air gap was greater than 10 cm，the average penetration depth of EFP increased by 26%（12 cm and 14 cm）compared with the concen- trated detonation product flow. The kinetic energy of EFP and concentrated detonation product flow per unit area through the hole wall on the shaped energy axis was calculated，it is found that when the air gap is small，the energy dissipation of concen- trated detonation product flow in the air is less than that of EFP plastic deformation，and the penetration effect of concentrated detonation product flow on the hole wall is better. When the air gap is large，the density and kinetic energy at the axis of the con- centrated detonation product flow are significantly reduced due to the spatial expansion of detonation products，while the EFP has high density and incompressibility，small energy dispersion and slow decay of kinetic energy，so the penetration effect of EFP on the hole wall is better than that of the concentrated detonation product flow. © 2024 Institute of Chemical Materials, China Academy of Engineering Physics. All rights reserved.