New Method for Monitoring and Correlating Cavitation Noise to Erosion Capability

For the purpose of obtaining a correlation between cavitation noise and damage, the source of damage, and its variance with flow parameters, was investigated. The individual cavitation pressure pulses were monitored by measuring the peak pulse amplitudes in a cavitating venturi. A pressure-bar probe and an acquisition system has been designed, constructed and used along with a commercial Kistler 601A probe for this purpose. The acoustic power derived from the pulse height spectra (PHS) was found to vary with the nth power of venturi throat velocity, where 6.8 < n < 10.5. The major component in this variation was the number of bubbles collapsing. This is a key factor in cavitation noise intensity variation, in this and other cavitating geometries. The acoustic power has been found to correlate linearly, with a small threshold, with the cavitation damage rate (MDPR) of 1100-0 aluminum. The feasibility of using cavitation erosion efficiency (ratio between erosion power and acoustic power) in predicting eventual cavitaion erosion rates in various geometries has been investigated.