Momentum and heat transfer of an inert gas jet to the melt in laser cutting

Abstract

The forces exerted by the gas jet on the molten layer in laser cutting are investigated theoretically by solving the equations of motion of the gas flow. The pressure distribution along the cutting front is found by the method of conformal mapping, while frictional forces are obtained from boundary layer theory. Both the pressure gradient and the frictional force are of the same importance for the melt ejection. For both contributions, simple scaling laws are presented. The cooling rate of the melt due to the gas stream is shown to be negligible.