Patent ID: 8455056

Claim:
A method of establishing a supersonic flame jet from a torch used for bonding material onto a surface, comprising the steps of: providing the torch with an elongated passage having a passage first section bounded by a passage sidewall that is substantially symmetrical about a central axis and a passage second section, the passage extending between a distal end and a proximal end; introducing a flow of oxygen into the passage first section with a rotational component of motion about the central axis so as to develop a swirling stream of the oxygen in the passage first section where the oxygen swirls about the central axis, this swirling oxygen being constrained against the passage sidewall; introducing at least one stream of gaseous fuel into the swirling oxygen, each of the at least one streams of fuel being offset from the central axis and from the passage sidewall so as to introduce the gaseous fuel into the oxygen within the passage first section in the vicinity of the location where the swirling action of the oxygen is greatest so as to mix the fuel and oxygen; limiting the length of the passage first section such that the swirling stream of the oxygen provides a sheath of unmixed oxygen along the passage sidewall extending at least through the passage distal end; and igniting the mixed fuel and oxygen so as to cause combustion as well as mixing of the fuel and oxygen within the passage first section, thereby providing a supersonic stream of combustion products exiting from the passage distal end.