Lasox, a hybrid laser-assisted oxygen-cutting technology, was developed not long time ago. The process is realized by the super sonic oxygen jet accomplished with laser beam with rather moderate power about 2kW. The major role is played by oxygen cutting jet. In certain, well known, minimum laser preheatening conditions stable heterogeneous iron-oxygen combustion reaction takes place on cutting front. One of the major problems is optimisation supersonic cutting head with de’Laval nozzle witch produces effective supersonic oxygen jet.
In this work simple principle of supersonic nozzle parameters selection for Lasox cutting process is presented. Postulated, that for good quality cuts the jet is to be over expanded or designed: smooth with a minimum of shock disks and other peculiarities. Flow inside cut kerf is to be supersonic, with good impact. The motion of the gas inside nozzle is considered as an isentropic process. These conditions are enough to construct nozzle geometry able to cut required plate thickness with required kerf width. In such a way method of supersonic nozzle geometry selection for thick section cutting Lasox is proposed. Known experimental points are in good agreement with theoretical prediction.