Numerical Simulations on Mechanism of Compressed-Air Jet Cutting the Soft Formation

Compressed-air jet cutting off soft formation was simulated by use of finite element explicit dynamic analysis program. The results of simulation experiments indicate that there are two inflections velocities during the jet penetration progress. Then the parameters including angle of arrival, traversing velocity, the number of jet bundle and diameter were simulated and the relations between various parameters and penetration efficiency were gained. Compact theory basis of designing bit was established in the pneumatic-injection reverse circulation drilling technology.