Testing Methods of Cavitation Erosion and the Impact of Component Material Selection on Pump Reliability

This paper presents in detail several cavitation erosion testing methods commonly used in the laboratory. The vibratory cavitation apparatus (G32) is described with its two variants, the direct method using a specimen attached to the vibrating tip of the ultrasonic horn and the alternative method using a fixed specimen facing the horn tip. In the cavitating jet apparatus (G134 and its variants), a jet is discharged at high pressure and velocity in a cell whose pressure may be controlled to adjust the cavitation number. This results in a shear type cavitation whose aggressiveness may be enhanced by a proper design of the nozzle shape and piping assembly. A high-speed cavitation tunnel equipped with a radial divergent test section is also presented. This particular test section generates an unsteady cavity attached to the nozzle exit with cavitation erosion damage concentrated in the cavity closure region. Usual testing procedures together with typical erosion patterns and mass loss results obtained in such facilities are also presented.