Modelling the laser fusion cutting process: II. Distribution of supersonicgas flow field inside the cut kerf

A mathematical model is developed to calculate the distribution of the gas flow field at the entrance, inside and exit of a laser cut kerf for inlet s tagnation pressures greater than or equal to5 bar for an inert assist gas j et exiting from a supersonic nozzle. A two-dimensional analytical method is adopted to locate approximately the position and shape of the detached sho ck above the cutting front surface according to the geometrical shape of th e cutting front. A method of two-dimensional characteristics is applied to calculate the gas flow field distribution along the cutting front. The calc ulated results of the flow field distribution are simulated by the computer and can be used to estimate and analyse the cut-edge quality under differe nt cutting conditions.