Ground or rock drilling - uses air jets emitted at half speed of sound surrounding high velocity water jet

摘要

The crushing or drilling of ground or rock is carried out with the aid of a high velocity jet of fluid issuing from a nozzle, surrounded by high velocity air jets. The speed of the air jet is half the speed of sound. The equipment consists of a drill (1) with drill rods (3) reaching down into the hole (2), with the jet nozzle (4) at the bottom end of the drill rods. The effect is to drive the air jet deeper into the rock, the greater the exit velocity of the air from the nozzle.