Abstract: A reverse-flow nozzle generates a cavitating and/or pulsed jet of pressurized liquid. The nozzle includes a body having an inlet for receiving a stream of liquid and a main channel through the body extending from the inlet to an outlet. A flow-reversing channel in the nozzle diverts a portion of the liquid from the main channel to a point downstream of a mixing chamber. The channel returns the diverted liquid back into the mixing chamber as a reverse-flow jet relative to a main stream of liquid flowing toward the outlet. This reverse-flow jet interacts with the main stream to generate the cavitating jet that discharges from the outlet. By angling the reverse-flow jet relative to the main stream, a naturally pulsed jet may be generated.

Abstract: An ultrasonic waterjet apparatus (10) has a mobile generator module (20) and a high-pressure water hose (40) for delivering high-pressure water from the mobile generator module (20) to a hand-held gun (50) with a trigger and an ultrasonic nozzle (60). An ultrasonic generator in the mobile generator module (20) transmits high-frequency electrical pulses to a piezoelectric or magnetostrictive transducer (62) which vibrates to modulate a high-pressure waterjet flowing through the nozzle (60). The waterjet exiting the ultrasonic nozzle (60) is pulsed into mini slugs of water, each of which imparts a waterhammer pressure on a target surface. The ultrasonic waterjet apparatus (10) may be used to cut and de-burr materials, to clean and de-coat surfaces, and to break rocks.

Abstract: A method of prepping a surface using a high-frequency forced pulsed waterjet entails generating a high-frequency signal having a frequency f using a high-frequency signal generator, applying the high-frequency signal to a transducer having a microtip to cause the microtip of the transducer to vibrate to thereby generate a forced pulsed waterjet through an exit orifice of a nozzle having an exit orifice diameter d and a length L. The forced pulsed waterjet prepares the surface to within a predetermined range of surface roughness. The surface roughness is determined by selecting operating parameters comprising a standoff distance (SD), a traverse velocity VTR of the nozzle, a water pressure P, a water flow rate Q, a length-to-diameter (L/d) ratio, a microtip-to-orifice distance (a), the frequency f, and an amplitude A of the high-frequency signal.

Abstract: An ultrasonic waterjet apparatus (10) has a mobile generator module (20) and a high-pressure water hose (40) for delivering high-pressure water from the mobile generator module (20) to a hand-held gun (50) with a trigger and an ultrasonic nozzle (60). An ultrasonic generator in the mobile generator module (20) transmits high-frequency electrical pulses to a piezoelectric or magnetostrictive transducer (62) which vibrates to modulate a high-pressure waterjet flowing through the nozzle (60). The waterjet exiting the ultrasonic nozzle (60) is pulsed into mini slugs of water, each of which imparts a waterhammer pressure on a target surface. The ultrasonic waterjet apparatus (10) may be used to cut and de-burr materials, to clean and de-coat surfaces, and to break rocks.

Abstract: An ultrasonic waterjet apparatus (10) has a mobile generator module (20) and a high-pressure water hose (40) for delivering high-pressure water from the mobile generator module (20) to a hand-held gun (50) with a trigger and an ultrasonic nozzle (60). An ultrasonic generator in the mobile generator module (20) transmits high-frequency electrical pulses to a piezoelectric or magnetostrictive transducer (62) which vibrates to modulate a high-pressure waterjet flowing through the nozzle (60). The waterjet exiting the ultrasonic nozzle (60) is pulsed into mini slugs of water, each of which imparts a waterhammer pressure on a target surface. The ultrasonic waterjet apparatus (10) may be used to cut and de-burr materials, to clean and de-coat surfaces, and to break rocks. The ultrasonic waterjet apparatus (10) performs these tasks with much greater efficiency than conventional continuous-flow waterjet systems because of the repetitive waterhammer effect.