Abstract:
A method and apparatus for controlling the coherence of a high-pressure fluid jet directed toward a selected surface. In one embodiment, the coherence is controlled by manipulating a turbulence level of the fluid forming the fluid jet. The turbulence level can be manipulated upstream or downstream of a nozzle orifice through which the fluid passes. For example, in one embodiment, the fluid is a first fluid and a secondary fluid is entrained with the first fluid. The resulting fluid jet, which includes both the primary and secondary fluids, can be directed toward the selected surface so as to cut, mill, roughen, peen, or otherwise treat the selected surface. The characteristics of the secondary fluid can be selected to either increase or decrease the coherence of the fluid jet. In other embodiments, turbulence generators, such as inverted conical channels, upstream orifices, protrusions and other devices can be positioned upstream of the nozzle orifice to control the coherence of the resulting fluid jet.